Dejan Lavbič’s publications and research snippets 63x

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2024 1x

Journal 1x

Jan Vasiljević and Dejan Lavbič. 2024. A Data-Driven Approach to Team Formation in Software Engineering Based on Personality Traits, Electronics, 13(1), pp. 178.
PDF full text Journal link Publication link SCIE (Q₂) SCIE (Q₃) SCIE (Q₂) IF₂₀₂₂ = 2,9 COBISS Google Scholar team formation personality traits data-driven approach Simulated Annealing Software Engineering

Collaboration among individuals with diverse skills and personalities is crucial to producing high-quality software. The success of any software project depends on the team’s cohesive functionality and mutual complementation. This study introduces a data-centric methodology for forming Software Engineering (SE) teams centred around personality traits. Our study analysed data from an SE course where 157 students in 31 teams worked through four project phases and were evaluated based on deliverables and instructor feedback. Using the Five-Factor Model (FFM) and a variety of statistical tests, we determined that teams with higher levels of extraversion and conscientiousness, and lower neuroticism, consistently performed better. We examined team members’ interactions and developed a predictive model using extreme gradient boosting. The model achieved a 74% accuracy rate in predicting inter-member satisfaction rankings. Through graphical explainability, the model underscored incompatibilities among members, notably those with differing levels of extraversion. Based on our findings, we introduce a team formation algorithm using Simulated Annealing (SA) built upon the insights derived from our predictive model and additional heuristics.

2023 3x

Journal 2x

Sandi Gec, Vlado Stankovski, Dejan Lavbič and Petar Kochovski. 2023. A Recommender System for Robust Smart Contract Template Classification, Sensors, 23(2).
HTML full text PDF full text Journal link Publication link SCIE (Q₂) SSCI (Q₂) SSCI (Q₂) IF₂₀₂₁ = 3,847 COBISS Google Scholar (2 citations)

IoT environments are becoming increasingly heterogeneous in terms of their distributions and included entities by collaboratively involving not only data centers known from Cloud computing but also the different types of third-party entities that can provide computing resources. To transparently provide such resources and facilitate trust between the involved entities, it is necessary to develop and implement smart contracts. However, when developing smart contracts, developers face many challenges and concerns, such as security, contracts’ correctness, a lack of documentation and/or design patterns, and others. To address this problem, we propose a new recommender system to facilitate the development and implementation of low-cost EVM-enabled smart contracts. The recommender system’s algorithm provides the smart contract developer with smart contract templates that match their requirements and that are relevant to the typology of the fog architecture. It mainly relies on OpenZeppelin, a modular, reusable, and secure smart contract library that we use when classifying the smart contracts. The evaluation results indicate that by using our solution, the smart contracts’ development times are overall reduced. Moreover, such smart contracts are sustainable for fog-computing IoT environments and applications in low-cost EVM-based ledgers. The recommender system has been successfully implemented in the ONTOCHAIN ecosystem, thus presenting its applicability.

Nikolay Vasilev and Dejan Lavbič. 2023. ‪Samoupravljana digitalna identiteta na verigi blokov Cardano‬, Uporabna informatika, 31(1).
PDF full text Journal link Publication link INSPEC COBISS Google Scholar

Problem današnjega interneta je, da je na voljo veliko informacij, ki jih nekdo nadzoruje (npr. oseba, organizacija), teh ljudi pa sploh ne poznamo. Samoupravljana identiteta je okvir zaupanja, pri katerem imajo entitete, kot so: ljudje, organizacije in abstraktne entitete, svoje popolnoma avtonomne identitete. Ta vrsta decentraliziranih digitalnih identitet s pomočjo decentraliziranih identifikatorjev in preverljivih poverilnic entitetam omogoča varno komunikacijo, nadzor nad lastnimi podatki ter izbiro, kaj in s kom bodo delili. Izmenjava podatkov se zgodi z uporabo verige blokov in tehnologije razpršene evidence, ki nam omogoča zaščitene in varne transakcije. S pomočjo te nove tehnologije in verige blokov Cardano smo razvili odprtokodno rešitev, ki bo študentom v pomoč pri izobraževalnem procesu. Ta rešitev pomaga predstaviti funkcionalnosti, ki nam jih decentralizirane digitalne identitete ponujajo pri izobraževanju. Z uporabo SWOT-analize smo primerjali sistem z že obstoječimi rešitvami, pri čemer pokažemo, da uporaba samoupravljene digitalne identitete naredi našo rešitev varnejšo, zmogljivejšo, cenejšo in uporabnejšo.

Conference 1x

Sandi Gec, Petar Kochovski, Vlado Stankovski and Dejan Lavbič. 2023. Project oriented teaching approach of decentralised applications for undergraduate students, Proceedings of the 15th International Conference on Education Technology and Computers (ICETC 2023), New York, NY, USA.
PDF full text Conference link Publication link COBISS Google Scholar decentralised application smart contract teaching

The emergence of new technologies and software engineering methodologies in the decentralised Web, referred to as Web 3.0, often requires using new approaches to supplement conventional development concepts such as object-oriented programming and design patterns. Therefore, it is essential to understand the blockchain fundamentals and modular development of distributed systems built from multiple components. This paper proposes a project-oriented teaching approach of smart contracts-based distributed applications (dApps) integrated into existing (Web 2.0) Web applications. First, we present the main overview of the Web programming course for a bachelor study program, prior knowledge requirements, and the characteristics of the lectures. Second, we define the dApp functional requirements for student projects that intend to consolidate the dApp theoretical concepts with a practical approach to complement the Web 3.0 concepts. The study of our teaching approach is based on an experiment where we thoroughly analyse performance on the course level, projects and individual students. The results indicate a high correlation between students’ performance in Web 2.0 and Web 3.0 development, and a higher degree of iterative process is also associated with better-performing students. Moreover, the student project outcomes also provide a basis for possible future course improvements.

2022 4x

Journal 4x

Marko Poženel, Aljaž Zrnec and Dejan Lavbič. 2022. Measuring how motivation affects information quality assessment: A gamification approach, PLOS ONE, 17(10).
HTML full text PDF full text Journal link Publication link SCI (Q₂) IF₂₀₂₁ = 3,752 COBISS

Purpose - Existing research on the measurability of information quality (IQ) has delivered poor results and demonstrated low inter-rater agreement measured by Intra-Class Correlation (ICC) in evaluating IQ dimensions. Low ICC could result in a questionable interpretation of IQ. The purpose of this paper is to analyse whether assessors’ motivation can facilitate ICC.

Sandi Gec, Petar Kochovski, Dejan Lavbič and Vlado Stankovski. 2022. Multi‐party smart contract for an AI services ecosystem: An application to smart construction, Concurrency and Computation: Practice and Experience.
PDF full text Journal link Publication link SCI (Q₃) SCI (Q₃) IF₂₀₂₀ = 1,536 COBISS WoS Google Scholar (1 citation)

Various smart applications, such as in the domain of smart construction, require the use of artificial intelligence (AI) based services. In order to support such environments, various AI/knowledge service provider and consumer ecosystems have started to emerge. Within such ecosystems, the goals are to improve the quality, reliability, dependability in terms of governance and trust in the data which is exchanged among the various actors, which must be supported by specific business models. This work introduces a novel multi-party smart contract (SC) that is designed to address the above mentioned goals. Specific service level agreements that illustrate the interactions among the AI service providers and consumers are also presented. The developed multi-party SC supports different pricing schemes, which are analyzed in detail against the goals of the study.

Slavko Žitnik, Karmen Kern Pipan, Miha Jesenko and Dejan Lavbič. 2022. Semantic reusable Web Components: A Use case in e-government interoperability, Uporabna informatika, 30(4).
HTML full text PDF full text Journal link Publication link INSPEC COBISS Google Scholar (1 citation)

Advancements in technology and software engineering strive to efficiently build robust technologies and deliver them as fast as possible. It has been shown that both could be achieved by reusing existing implementations, libraries, components, and even frameworks. In the field of public administration, which needs to follow and implement national and EU regulations, it is essential to not only have compatible semantic data structures and processes but also to enable cross-sector and cross-border integrations. In this paper, we present the Digital Europe for All project, more specifically, a use case of a reusable prototype - A web component based on semantic data representation. We show that the component can be easily integrated into an arbitrary Web site and supports arbitrary evidence types, represented using the project’s ontologies. Reusing such components enables faster creation of interoperable digital public services and opens new opportunities, better mobility, faster processes, and reduced implementation costs.

Aljaž Zrnec, Marko Poženel and Dejan Lavbič. 2022. Users’ ability to perceive misinformation: An information quality assessment approach, Information Processing & Management, 59(1).
HTML full text PDF full text Journal link Publication link arXiv link SCIE (Q₁) SSCI (Q₁) IF₂₀₂₀ = 6,222 COBISS WoS Google Scholar (24 citations) Big Five personality traits Case study Fake news Fake news detection Information quality Misinformation

Digital information exchange enables quick creation and sharing of information and thus changes existing habits. Social media is becoming the main source of news for end-users replacing traditional media. This also enables the proliferation of fake news, which misinforms readers and is used to serve the interests of the creators. As a result, automated fake news detection systems are attracting attention. However, automatic fake news detection presents a major challenge; content evaluation is increasingly becoming the responsibility of the end-user. Thus, in the present study we used information quality (IQ) as an instrument to investigate how users can detect fake news. Specifically, we examined how users perceive fake news in the form of shorter paragraphs on individual IQ dimensions. We also investigated which user characteristics might affect fake news detection. We performed an empirical study with 1123 users, who evaluated randomly generated stories with statements of various level of correctness by individual IQ dimensions. The results reveal that IQ can be used as a tool for fake news detection. Our findings show that (1) domain knowledge has a positive impact on fake news detection; (2) education in combination with domain knowledge improves fake news detection; and (3) personality trait conscientiousness contributes significantly to fake news detection in all dimensions.

2021 1x

Journal 1x

Martin Schweinsberg, Michael Feldman, Nicola Staub, Olmo R. van den Akker, Robbie C. M. van Aert, Marcel A. L. M. van Assen, Yang Liu, Tim Althoff, Jeffrey Heer, Alex Kale, Zainab Mohamed, Hashem Amireh, Vaishali Venkatesh Prasad, Abraham Bernstein, Emily Robinson, Kaisa Snellman, S. Amy Sommer, Sarah M. G. Otner, David Robinson, Nikhil Madan, Raphael Silberzahn, Pavel Goldstein, Warren Tierney, Toshio Murase, Benjamin Mandl, Domenico Viganola, Carolin Strobl, Catherine B. C. Schaumans, Stijn Kelchtermans, Chan Naseeb, S. Mason Garrison, Tal Yarkoni, C. S. Richard Chan, Prestone Adie, Paulius Alaburda, Casper Albers, Sara Alspaugh, Jeff Alstott, Andrew A. Nelson, Eduardo Ariño de la Rubia, Adbi Arzi, Štěpán Bahník, Jason Baik, Laura Winther Balling, Sachin Banker, David AA Baranger, Dale J. Barr, Brenda Barros-Rivera, Matt Bauer, Enuh Blaise, Lisa Boelen, Katerina Bohle Carbonell, Robert A. Briers, Oliver Burkhard, Miguel-Angel Canela, Laura Castrillo, Timothy Catlett, Olivia Chen, Michael Clark, Brent Cohn, Alex Coppock, Natàlia Cugueró-Escofet, Paul G. Curran, Wilson Cyrus-Lai, David Dai, Giulio Valentino Dalla Riva, Henrik Danielsson, Rosaria de F. S. M. Russo, Niko de Silva, Curdin Derungs, Frank Dondelinger, Carolina Duarte de Souza, B. Tyson Dube, Marina Dubova, Ben Mark Dunn, Peter Adriaan Edelsbrunner, Sara Finley, Nick Fox, Timo Gnambs, Yuanyuan Gong, Erin Grand, Brandon Greenawalt, Dan Han, Paul H. P. Hanel, Antony B. Hong, David Hood, Justin Hsueh, Lilian Huang, Kent N. Hui, Keith A. Hultman, Azka Javaid, Lily Ji Jiang, Jonathan Jong, Jash Kamdar, David Kane, Gregor Kappler, Erikson Kaszubowski, Christopher M. Kavanagh, Madian Khabsa, Bennett Kleinberg, Jens Kouros, Heather Krause, Angelos-Miltiadis Krypotos, Dejan Lavbič, Rui Ling Lee, Timothy Leffel, Wei Yang Lim, Silvia Liverani, Bianca Loh, Dorte Lønsmann, Jia Wei Low, Alton Lu, Kyle MacDonald, Christopher R. Madan, Lasse Hjorth Madsen, Christina Maimone, Alexandra Mangold, Adrienne Marshall, Helena Ester Matskewich, Kimia Mavon, Katherine L. McLain, Amelia A. McNamara, Mhairi McNeill, Ulf Mertens, David Miller, Ben Moore, Andrew Moore, Eric Nantz, Ziauddin Nasrullah, Valentina Nejkovic, Colleen S. Nell, Andrew Arthur Nelson, Gustav Nilsonne, Rory Nolan, Christopher E. O'Brien, Patrick O'Neill, Kieran O'Shea, Toto Olita, Jahna Otterbacher, Diana Palsetia, Bianca Pereira, Ivan Pozdniakov, John Protzko, Jean-Nicolas Reyt, Travis Riddle, Amal (Akmal) Ridhwan Omar Ali, Ivan Ropovik, Joshua M. Rosenberg, Stephane Rothen, Michael Schulte-Mecklenbeck, Nirek Sharma, Gordon Shotwell, Martin Skarzynski, William Stedden, Victoria Stodden, Martin A. Stoffel, Scott Stoltzman, Subashini Subbaiah, Rachael Tatman, Paul H. Thibodeau, Sabina Tomkins, Ana Valdivia, Gerrieke B. Druijff-van de Woestijne, Laura Viana, Florence Villesèche, W. Duncan Wadsworth, Florian Wanders, Krista Watts, Jason D. Wells, Christopher E. Whelpley, Andy Won, Lawrence Wu, Arthur Yip, Casey Youngflesh, Ju-Chi Yu, Arash Zandian, Leilei Zhang, Chava Zibman and Eric Luis Uhlmann. 2021. Same data, different conclusions: Radical dispersion in empirical results when independent analysts operationalize and test the same hypothesis, Organizational Behavior and Human Decision Processes, 165, pp. 228--249.
PDF full text Journal link Publication link SSCI (Q₂) SSCI (Q₂) SSCI (Q₃) IF₂₀₁₉ = 2,304 COBISS WoS Google Scholar (88 citations) Analysis-contingent results Crowdsourcing data analysis Research reliability Researcher degrees of freedom Scientific robustness Scientific transparency

In this crowdsourced initiative, independent analysts used the same dataset to test two hypotheses regarding the effects of scientists’ gender and professional status on verbosity during group meetings. Not only the analytic approach but also the operationalizations of key variables were left unconstrained and up to individual analysts. For instance, analysts could choose to operationalize status as job title, institutional ranking, citation counts, or some combination. To maximize transparency regarding the process by which analytic choices are made, the analysts used a platform we developed called DataExplained to justify both preferred and rejected analytic paths in real time. Analyses lacking sufficient detail, reproducible code, or with statistical errors were excluded, resulting in 29 analyses in the final sample. Researchers reported radically different analyses and dispersed empirical outcomes, in a number of cases obtaining significant effects in opposite directions for the same research question. A Boba multiverse analysis demonstrates that decisions about how to operationalize variables explain variability in outcomes above and beyond statistical choices (e.g., covariates). Subjective researcher decisions play a critical role in driving the reported empirical results, underscoring the need for open data, systematic robustness checks, and transparency regarding both analytic paths taken and not taken. Implications for organizations and leaders, whose decision making relies in part on scientific findings, consulting reports, and internal analyses by data scientists, are discussed.

2019 2x

Journal 1x

Sandi Gec, Dejan Lavbič and Vlado Stankovski. 2019. Do lahkih pametnih pogodb s pametnimi preroki, Uporabna informatika, 27(4), pp. 161–166.
PDF full text Journal link Publication link INSPEC Google Scholar pametna pogodba pametni prerok tehnologija veriženja blokov

Od razvoja tehnologije veriženja blokov ter pristopov, kot so pametne pogodbe, je zanimanje za vključitev tovrstnih pristopov v obstoječe arhitekture računalništva v oblaku v vzponu. Pametne pogodbe so v splošnem porazdeljene aplikacije, ki omogočajo prenos digitalnih sredstev med pogodbenimi strankami po vnaprej dogovorjenih pogojih, so se izkazale kot obetavne zlasti zaradi transparentnega izvajanja med različnimi deležniki. S povečanjem algoritmičnih kompleksnosti funkcionalnosti, kot v našem primeru metoda za izvajanje sporazuma na ravni storitve v pametnih pogodbah, lahko postane vprašljiva smortnost izvedljivosti predvsem s stroškovnega stališča, zato je mogoče uporabiti sodoben pristop komunikacije pametnih pogodb z zunanjimi viri, ki ga imenujemo pametni preroki. Poenostavitev pametnih pogodb je mogoča, če del jedra funkcionalnosti ali algoritma izvajamo zunaj verige. V tem prispevku predlagamo novo metodo za izvajanje sporazuma na ravni storitve na pametni pogodbi s prenosom operacij z verige na namenske storitve zunaj verige z uporabo pametnih prerokov. Predlagana metoda dokazuje, da je mogoče zmanjšati skupne stroške izvajanja pametne pogodbe in hkrati izboljšuje raven distribucije rešitve.

Book chapter 1x

Marko Poženel and Dejan Lavbič. 2019. Discovering Language of Stocks, Frontiers in Artificial Intelligence and Applications - Databases and Information Systems X315, pp. 243–258, IOS Press.
HTML full text PDF full text Book link Publication link arXiv link COBISS Google Scholar (2 citations) Japanese candlesticks NLP Stock price prediction Trading strategy Word2Vec

Stock prediction has always been attractive area for researchers and investors since the financial gains can be substantial. However, stock prediction can be a challenging task since stocks are influenced by a multitude of factors whose influence vary rapidly through time. This paper proposes a novel approach (Word2Vec) for stock trend prediction combining NLP and Japanese candlesticks. First, we create a simple language of Japanese candlesticks from the source OHLC data. Then, sentences of words are used to train the NLP Word2Vec model where training data classification also takes into account trading commissions. Finally, the model is used to predict trading actions. The proposed approach was compared to three trading models Buy & Hold, MA and MACD according to the yield achieved. We first evaluated Word2Vec on three shares of Apple, Microsoft and Coca-Cola where it outperformed the comparative models. Next we evaluated Word2Vec on stocks from Russell Top 50 Index where our Word2Vec method was also very successful in test phase and only fall behind the Buy & Hold method in validation phase. Word2Vec achieved positive results in all scenarios while the average yields of MA and MACD were still lower compared to Word2Vec.

2018 3x

Journal 1x

Jan Robas and Dejan Lavbič. 2018. Poizvedovanje po povezanih podatkih s porazdelitvijo dela med strežnikom in odjemalcem, Uporabna informatika, 26(2), pp. 54–64.
HTML full text PDF full text Journal link Publication link INSPEC COBISS Google Scholar povezani podatki procesiranje na odjemalcu semantični splet SPARQL spletne tehnologije

Na spletu je veliko podatkov, ki so objavljeni na različnih mestih v različnih, nezdružljivih oblikah. Zaradi tega nad njimi ne moremo izvajati poizvedb. Iskanje odgovora na specifično vprašanje ponavadi terja iskanje po ključnih besedah, branje in tolmačenje vsebine. To lahko rešimo tako, da uporabimo povezane podatke. Problem pri tem je dostopnost in učinkovitost poizvedovanja. V tem članku predstavimo obstoječo rešitev, ki omogoča poizvedovanje po povezanih podatkih tako, da je delo porazdeljeno med strežnikom in odjemalcem. Poleg tega predstavimo obstoječo razširitev, ki poveča učinkovitost in ne nazadnje našo lastno razširitev, s katero poskušamo učinkovitost še izboljšati. Našo razširitev primerjamo z že obstoječo razširitvijo in z osnovno različico omenjene rešitve.

Conference 2x

Sandi Gec, Dejan Lavbič, Marko Bajec and Vlado Stankovski. 2018. Smart contracts for container based video conferencing services: Architecture and implementation, Proceedings of 15th International Conference on the Economics of Grids, Clouds, Systems, and Services (GECON 2018), Pisa, Italy.
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Today, container-based virtualization is very popular due to the lightweight nature of containers and the ability to use them flexibly in various heterogeneously composed systems. This makes it possible to collaboratively develop services by sharing various types of resources, such as infrastructures, software and digitalized content. In this work, our home made video-conferencing (VC) system is used to study resource usage optimisation in business context. An application like this, does not provide monetization possibilities to all involved stakeholders including end users, cloud providers, software engineers and similar. Blockchain related technologies, such as Smart Contracts (SC) offer a possibility to address some of these needs. We introduce a novel architecture for monetization of added-value according to preferences of the stakeholders that participate in joint software service offers. The developed architecture facilitates use case scenarios of service and resource offers according to fixed and dynamic pricing schemes, fixed usage period, prepaid quota for flexible usage, division of income, consensual decisions among collaborative service providers, and constrained based usage of resources or services. Our container-based VC service, which is based on the Jitsi Meet Open Source software is used to demonstrate the proposed architecture and the benefits of the investigated use cases.

Marko Poženel and Dejan Lavbič. 2018. What language do stocks speak?, Databases and Information Systems, DB&IS 2018, Communications in Computer and Information Science, Trakai, Vilnius.
HTML full text PDF full text PPT slides Conference link Publication link COBISS Google Scholar NLP Stock price prediction Trading strategy Word2Vec

Stock prediction is a challenging and chaotic research area where many variables are included with their effects being complex to determine. Nevertheless, stock value prediction is still very appealing for researchers and investors since it might be profitable, yet the number of published research papers remains to be relatively small. The employment of advanced data analysis techniques has already been suggested by previous researches, such as the use of neural networks for stock price prediction, but practical implications of the the majority of approaches are limited as they are concerned mainly with a prediction accuracy and less with the success in real trading with consideration of trading fees. We propose a novel approach for stock trend prediction that combines Japanese candlesticks (OHLC trading data) and neural network based group of models Word2Vec. Word2Vec is usually utilized to produce word embeddings in natural language processing tasks, while we adopt it for acquiring semantic context of words in candlesticks’ sequence, where clustered candlesticks represent stock’s words. The approach is employed for the extraction of useful information from large sets of OHLC trading data to improve prediction accuracy. In evaluation of our approach we define a trading strategy and compare our approach with other popular prediction models – Buy & Hold, MA and MACD. The evaluation results on Russell Top 50 index are encouraging – the proposed Word2Vec approach outperformed all compared models on a test set with a statistical significance.

2017 5x

Journal 4x

Miloš Fidler and Dejan Lavbič. 2017. Improving information quality of Wikipedia articles with cooperative principle, Online Information Review, 41(6), pp. 797–811.
HTML full text PDF full text Journal link Publication link arXiv link SCIE (Q₃) SSCI (Q₂) IF₂₀₁₇ = 1,675 COBISS WoS Google Scholar (13 citations) Conversation maxims Cooperative principle Improving information quality Information quality assessment and analysis Interrater reliability Presenting information in relevant way

Purpose: The purpose of this paper is to investigate the impact of cooperative principle on the information quality (IQ) by making objects more relevant for consumer needs, in particular case Wikipedia articles for students. Design/methodology/approach: The authors performed a quantitative study with participants being invited to complete an online survey. Each rater evaluated three selected and re-written articles from Wikipedia by four IQ dimensions (accuracy, completeness, objectivity, and representation). Grice’s maxims and submaxims were used to re-write articles and make them more relevant for student cognitive needs. The results were analyzed with statistical methods of mean, standard deviation, Cronbach’s α, and ICC (two-way random model of single measure). Findings: The study demonstrates that Wikipedia articles can be made more relevant for student needs by using cooperative principle with increase in IQ and also achieving higher consistency of students’ scores as recent research. In particular, students in the research perceived the abstract, constructed with cooperative principle, more objective and complete as reported in recent research. Practical implications: The work can benefit encyclopedia editors to improve IQ of existing articles as well as consumers that would obtain more relevant information in less reading time. Originality/value: This is one of the first attempts to empirically investigate the application of cooperate principle to make objects more relevant for consumer needs and impact of this on IQ. IQ improvement evidence is provided and impacts on IQ dimensions such as objectivity, completeness, accuracy, and representation for research community to validate and compare results.

Dejan Lavbič, Tadej Matek and Aljaž Zrnec. 2017. Learning SQL with Artificial Intelligent Aided Approach, International Journal of Information and Education Technology, 7(11), pp. 803–808.
PDF full text Journal link Publication link INSPEC COBISS Google Scholar Improving classroom teaching Intelligent Tutoring Systems Interactive learning environments Programming and programming languages Recommender system SQL learning

Efficient data manipulation and retrieval is a fundamental part of many business processes in the majority of todays’ companies. SQL, as a standard, is widely adopted and well accepted in this area. Students who set out to learn SQL frequently face difficulties. The learning process is to some extent inefficient, as the student’s knowledge is afterwards often inadequate. Several computer-aided systems have been developed to alleviate the problem. However, most of them are static and rigid, because the system’s knowledge is encoded manually. We propose a new system based on past attempts and solutions to SQL exercises. The proposed system is flexible and dynamic, as it adapts to the individual student and requires minimal intervention from domain experts. We show that the system is beneficial, in particular to students with low prior knowledge.

Dejan Lavbič, Tadej Matek and Aljaž Zrnec. 2017. Recommender system for learning SQL using hints, Interactive Learning Environments, 25(8), pp. 1048–1064.
HTML full text PDF full text Journal link Publication link arXiv link SSCI (Q₂) IF₂₀₁₇ = 1,604 COBISS WoS Google Scholar (19 citations) Improving classroom teaching Intelligent Tutoring Systems Interactive learning environments Programming and programming languages Recommender system SQL learning

Today’s software industry requires individuals who are proficient in as many programming languages as possible. Structured query language (SQL), as an adopted standard, is no exception, as it is the most widely used query language to retrieve and manipulate data. However, the process of learning SQL turns out to be challenging. The need for a computer-aided solution to help users learn SQL and improve their proficiency is vital. In this study, we present a new approach to help users conceptualize basic building blocks of the language faster and more efficiently. The adaptive design of the proposed approach aids users in learning SQL by supporting their own path to the solution and employing successful previous attempts, while not enforcing the ideal solution provided by the instructor. Furthermore, we perform an empirical evaluation with 93 participants and demonstrate that the employment of hints is successful, being especially beneficial for users with lower prior knowledge.

Aljaž Zrnec and Dejan Lavbič. 2017. Social network aided plagiarism detection: Social network aided plagiarism detection, British Journal of Educational Technology, 48(1), pp. 113–128.
HTML full text PDF full text Journal link Publication link arXiv link SSCI (Q₁) IF₂₀₁₇ = 2,729 COBISS WoS Google Scholar (16 citations) Case study Assessment Facilitation Learning management systems Plagiarism detection process Plagiarism visualization Social Network Analysis Student-centredness

The prevalence of different kinds of electronic devices and the volume of content on the Web have increased the amount of plagiarism, which is considered an unethical act. If we want to be efficient in the detection and prevention of these acts, we have to improve today’s methods of discovering plagiarism. The paper presents a research study where a framework for the improved detection of plagiarism is proposed. The framework focuses on the integration of social network information, information from the Web, and an advanced semantically enriched visualization of information about authors and documents that enables the exploration of obtained data by seeking of advanced patterns of plagiarism. To support the proposed framework, a special software tool was also developed. The statistical evaluation confirmed that the employment of social network analysis and advanced visualization techniques led to improvements in the confirmation and investigation stages of the plagiarism detection process, thereby enhancing the overall efficiency of the plagiarism detection process.

Conference 1x

Slavko Žitnik, Marko Bajec and Dejan Lavbič. 2017. LogMap+ : Relational data enrichment and linked data resources matching, 11th International conference on research challenges in Information Science (RCIS 2017), Brighton, UK.
PDF full text Conference link COBISS Google Scholar (2 citations) OAEI ontology mapping ontology matching relational database

Relational database to ontology mapping and ontology matching techniques are mostly addressed separately, even though it is known that the real power of semantic data lies in data interconnection. The latter is especially important when designing a new ontology, which often includes at least some of the concepts that already exist in the linked open data cloud. Thus, in this paper we describe a new end-to-end tool LogMap+ for transformation of relational data into an ontology and matching it against a pre-existent semantic source. Apart from offering the efficient web-based application, the main contributions are the improvements of the domain specific LogMap system. We evaluate our general tool against OAEI 2014 challenge datasets and achieve comparable results to the top performing algorithms and also outperform the domain specific LogMap tool.

2016 2x

Journal 2x

Tadej Matek and Dejan Lavbič. 2016. Adaptivni pristop k učenju jezika SQL, Uporabna informatika, 24(2), pp. 81–93.
PDF full text Journal link Publication link INSPEC COBISS inteligentni sistemi za učenje odločitveni proces Markova priporočilni sistemi razčlenjevalnik jezika SQL strojno učenje učenje jezika SQL

Jezik SQL je danes standard na področju poizvedovanja in manipulacije s podatki. Večina podjetij aktivno uporablja jezik SQL za podporo delovanja informacijskih sistemov, zato so potrebe po usposabljanju velike. Sam proces učenja jezika SQL je težaven, saj pogosto prihaja do napačnega razumevanja temeljnih konceptov jezika. V okviru naše raziskave smo se lotili razvoja adaptivnega sistema za generiranje namigov kot pomoč pri procesu učenja. Sistema uporablja informacije iz zgodovinskih podatkov, iz preteklih poskusov reševanja nalog iz jezika SQL. Za odkrivanje znanja, skritega v podatkih, smo uporabili odločitvene procese Markova, ki omogočajo napovedovanje v negotovih razmerah. Poleg sistema smo razvili tudi komponento za procesiranje jezika SQL ter preprost spletni vmesnik. Preprosta evalvacija je pokazala, da je sistem zmožen generirati namige, prilagojene posameznemu študentu.

Olegas Vasilecas, Diana Kalibatiene and Dejan Lavbič. 2016. Rule- and context-based dynamic business process modelling and simulation, Journal of Systems and Software, 122, pp. 1–15.
HTML full text PDF full text Journal link Publication link arXiv link SCIE (Q₁) SCIE (Q₁) IF₂₀₁₇ = 2,444 COBISS WoS Google Scholar (51 citations) Business Process Modelling Business Rules Context Dynamic Business Process Simulation

The traditional approach used to implement a business process (BP) in today’s information systems (IS) no longer covers the actual needs of the dynamically changing business. Therefore, a necessity for a new approach of dynamic business process (DBP) modelling and simulation has arisen. To date, existing approaches to DBP modelling and simulation have been incomplete, i.e. they lack theory or a case study or both. Furthermore, there is no commonly accepted definition of BDP. Current BP modelling tools are suitable almost solely for the modelling and simulation of a static BP that strictly prescribes which activities, and in which sequence, to execute. Usually, a DBP is not defined strictly at the beginning of its execution, and it changes under new conditions at runtime. In our paper, we propose six requirements of DBP and an approach for rule- and context-based DBP modelling and simulation. The approach is based on changing BP rules, BP actions and their sequences at process instance runtime, according to the new business system context. Based on the proposed approach, a reference architecture and prototype of a DBP simulation tool were developed. Modelling and simulation were carried out using this prototype, and the case study shows correspondence to the needs of dynamically changing business, as well as possibilities for modelling and simulating DBP.

2015 3x

Conference 3x

Miloš Fidler and Dejan Lavbič. 2015. Research About Measurability of Information Quality, 10th International Conference on Knowledge Management in Organisations (KMO 2015), Slovenia, Maribor.
PDF full text Conference link Publication link COBISS Google Scholar (1 citation) Information quality Accuracy Big data Completeness Consistency Information quality dimensions Inter rater reliability Objectivity

This article will discuss on going research about Information Quality (IQ). Raters evaluating various IQ dimensions (accuracy, completeness, objectivity …) of same object showed low agreement level, therefore making IQ not measurable. Increase of IQ measurability to sufficient level would present an opportunity for guidelines to replace information of low with high quality. Speculations why IQ dimensions are not measurable have been made but at the same time mechanisms that improve agreement level have been proposed by researchers for validation. Moreover context in which information is being evaluated has not been yet addressed by existing research. This article will describe and explain a study that aims to create a robust model that will validate and measure effect of three different IQ aspects. Although this article is still work in progress, current results regarding research construction and preliminary testing will be presented as well as future steps.

Ana Bastinos Šaša and Dejan Lavbič. 2015. SPARQL-based framework for semantically-based event processing, Proceedings of the 25th International Conference on Information Modelling and Knowledge Bases (EJC 2015), Maribor, Slovenia.
PDF full text Conference link COBISS Google Scholar (1 citation) ontology SPARQL complex event event processing OWL RDF

Event-driven architecture and complex event processing have become important topics in achieving business reactivity and proactivity. Even though many technologies to support this have been developed, there is still a need for providing support for complex events based on different levels of required expressivity. On the other hand, semantic technologies and semantic-based systems have emerged and are becoming more and more used, whereas there is no recognized solution for event processing in information systems based on semantic technologies. In this paper, we address these issues. We present a framework for ontology-based support for complex events, which allows for semantically enriched event definitions and automatic recognition. In order to automatically recognize complex events, an appropriate event definition basis has to be defined. The paper represents a continuation of our previous work by enhancing this basis and developing a SPARQL-based framework to provide a richer mechanism for event definitions and more efficient event detection. As a proof-of-concept, we provide an implementation of this framework using the semantic integration platform - Information Workbench. The implementation is available as an app that runs on top of the Information Workbench platform.

Aljaž Zrnec and Dejan Lavbič. 2015. The Role of Social Connections in Plagiarism Detection, Learning technology for education in cloud (LTEC 2015), Maribor, Slovenia.
PDF full text Conference link COBISS WoS Google Scholar (1 citation) integration plagiarism detection process plagiarism visualisation social network anaylsis

Plagiarism is considered as an unethical act. Over the past few years its rate has increased considerably due to a widespread access to electronic documents on the Web. Existing tools for plagiarism detection are not efficient enough and if we want to successfully prevent these kind of acts we must improve today’s plagiarism detection approaches. The paper proposes a framework for improved detection of plagiarism, where we focus on integration of information from social networks, information from the Web and semantically enriched visualization of information about authors and plagiates. Visualization enables exploring data and seeking of advanced patterns of plagiarism. We also developed a special tool to support the proposed framework. The results of evaluation confirmed our hypothesis that employment of social network analysis and advanced visualization techniques improves plagiarism detection process.

2014 1x

Conference 1x

Andraž Hribernik, Lorand Dali, Dušan Omerčević and Dejan Lavbič. 2014. Applying multi-armed bandit on top of content similarity recommendation engine, Data science for news publishing at KDD 2014 (NewsKDD 2014), New York, USA.
PDF full text Conference link COBISS Google Scholar (1 citation) exploration vs. exploitation mobile news recommendation systems

One of the goals of every news publisher is to prolong users’ browsing sessions by convincing them to read additional content besides the initially requested. Consequently, most news publishers use recommendation engines to keep users engaged by recommending them content which they might like to read next. In this paper we present how to improve an existing news recommendation system deployed on the mobile news site of one of Zemanta’s partners. With this publisher the users are browsing news sequentially by scrolling through a continuous stream of items on their mobile devices. Our goal is to order the recommended items in a way to increase probability that the users will click one them and read them. The existing system orders the recommendations by similarity to the article that the user is currently reading. We build on top of the content-similarity approach by also estimating the probability that the recommended item will be clicked. We use click-through data, and take a Bayesian approach to estimate the probability of a click; moreover, we propose the use of hierarchical models as a way of including data from contextually similar sessions into the estimation. The recommendations are performed using a multi-armed bandit approach. We try to find a trade-off between “exploitation” of items likely to perform well and “exploration” of items where not much data is available. When evaluated on data collected from a mobile news publisher, the proposed methods showed significant improvements compared to the existing system.

2013 4x

Journal 1x

Slavko Žitnik, Lovro Šubelj, Dejan Lavbič, Olegas Vasilecas and Marko Bajec. 2013. General Context-Aware Data Matching and Merging Framework, Informatica, 24(1), pp. 119–152.
HTML full text PDF full text Journal link Publication link arXiv link SCIE (Q₃) SCIE (Q₂) IF₂₀₁₃ = 0,901 COBISS WoS Google Scholar (4 citations) trust entity resolution ontologies redundancy elimination semantic elevation

Due to numerous public information sources and services, many methods to combine heterogeneous data were proposed recently. However, general end-to-end solutions are still rare, especially systems taking into account different context dimensions. Therefore, the techniques often prove insufficient or are limited to a certain domain. In this paper we briefly review and rigorously evaluate a general framework for data matching and merging. The framework employs collective entity resolution and redundancy elimination using three dimensions of context types. In order to achieve domain independent results, data is enriched with semantics and trust. However, the main contribution of the paper is evaluation on five public domain-incompatible datasets. Furthermore, we introduce additional attribute, relationship, semantic and trust metrics, which allow complete framework management. Besides overall results improvement within the framework, metrics could be of independent interest.

Conference 3x

Miloš Pavković, Dražen Drašković, Lovro Šubelj, Slavko Žitnik, Dejan Lavbič, Marko Janković, Jelica Protić and Boško Nikolić. 2013. Intelligent techniques for searching Internet forums, Proceedings of the 22nd International Electrotechnical and Computer Science Conference (ERK 2013), Portorož, Slovenia.
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Aljaž Zrnec, Dejan Lavbič, Neli Blagus, Marko Janković and Marko Bajec. 2013. Podatkovne baze vrste triplestore, Zbornik prispevkov 20. konference Dnevi slovenske informatike (DSI 2013), Portorož, Slovenia.
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Dejan Lavbič, Slavko Žitnik, Lovro Šubelj, Aleš Kumer, Aljaž Zrnec and Marko Bajec. 2013. Traversal and Relations Discovery among Business Entities and People using Semantic Web Technologies and Trust Management, Databases and Information Systems VII, 10th International Baltic Conference on Databases and Information Systems (Baltic DB&IS 2012), Vilnius, Lithuania.
PDF full text COBISS WoS Google Scholar (6 citations)

There are several data silos containing information about business entities and people but are not semantically connected. If in integration process of data sources trust management is also employed than we can expect much higher success rate in relations discovery among entities. Majority of current mash-up approaches that deal with integration of information from several data sources omit or don’t fully address the aspect of trust. In this paper we discuss semantic integration of personal and business information from various data sources coupled with trust layer. The resulting system has higher and more defined solidity while trust for single entity and also for data source is defined. The case study presented in the paper focuses on integration of personal information from data sources mainly maintained by government authorities who have higher trustability than information from social networks, but we also include other less trusted sources. The developed SocioLeaks system allows users traversal and further relation discovery in a graph based manner.

2012 5x

Journal 2x

Dejan Lavbič and Marko Bajec. 2012. Employing semantic web technologies in financial instruments trading, International journal of new computer architectures and their applications, 2(1), pp. 167–182.
PDF full text Journal link Publication link INSPEC COBISS Google Scholar (6 citations) financial instruments ontology rapid ontology development Semantic web trading strategies

The lack of rapid approaches in ontology development led us to define Rapid Ontology Development (ROD) approach. The following approach includes the development process and constant evaluation of the steps in the process. The ROD approach was then applied to development of Financial Instruments and Trading Strategies (FITS) ontology. We pointed out that ontology development process does not conclude with successful definition of schematic part of ontology, but that developers should continue with post development activities where additional axiomatic information and instances with dynamic imports from various sources are defined. The result is executable ontology as part of Semantic Web application that can employ data from several data sources. The overall process of ontology development presented in this paper is suitable for users without extensive technical and programming skills.

Dejan Lavbič. 2012. Rapid ontology development model based on rule management approach in business applications, Informatica, 36(1), pp. 115–116.
PDF full text Journal link Publication link INSPEC COBISS Google Scholar (2 citations) Semantic web Business rules Methodologies for ontology development Ontologies Ontology evaluation Rapid ontology development ROD

In this paper rapid ontology development with emphasis on facilitating development with constant evaluation of steps in the process of ontology development is presented. The review of related work pointed out that existing methodologies for ontology development are complex and high level of technical knowledge is required. Business users and developers usually don’t pose such knowledge therefore ontology completeness indicator was introduced in this approach. The role of this indicator is to guide developer throughout the development process and constantly aid user with recommendations to progress to next step and improve the quality of ontology. While evaluating the ontology, several aspects are considered; from description, partition, consistency, redundancy and to anomaly. The approach was verified on Financial Instruments and Trading Strategies (FITS) ontology and compared to other approaches.

Conference 3x

Slavko Žitnik, Lovro Šubelj, Dejan Lavbič, Aljaž Zrnec and Marko Bajec. 2012. Collective information extraction using first-order probabilistic models, ACM International Conference Proceeding Series (5th Balkan Conference in Informatics (BCI 2012)), Novi Sad, Serbia.
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Traditional information extraction (IE) tasks roughly consist of named-entity recognition, relation extraction and coreference resolution. Much work in this area focuses primarily on separate subtasks where best performance can be achieved only on specialized domains. In this paper we present a collective IE approach combining all three tasks by employing linear-chain conditional random fields. The usage of probabilistic models enables us to easily communicate between tasks on the fly and error correction during the iterative process execution. We introduce a novel iterative-based IE system architecture with additional semantic and collective feature functions. Proposed system is evaluated against real-world data set, introduced in the paper, and results are better over traditional approaches on two tested tasks by error reduction and performance improvements.

Lovro Šubelj, Slavko Žitnik, Aljaž Zrnec, Aleš Kumer, Bojan Klemenc, Dejan Lavbič and Marko Bajec. 2012. Lastnosti velikih realnih omrežij in primeri uporabe, Zbornik prispevkov 19. konference Dnevi slovenske informatike (DSI 2012), Portorož, Slovenia.
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V zadnjih letih so postala omrežja izjemno popularna, saj predstavljajo močno orodje za predstavitev in analizo kompleksnih sistemov, sestavljenih iz velikega števila med seboj povezanih komponent. Takšne sisteme najdemo tako v realnem kot navideznem svetu, v naravi in tehnologiji, in so trenutno predmet številnih analiz in študij. Teorija omrežij je v preteklosti ponudila že številna pomembna spoznanja kot na primer fenomen majhnega sveta, odpornost tehnoloških omrežij in obstoj komun v socialnih omrežjih. Poleg slednjega pa je omogočila razlago različnih dinamičnih procesov kot na primer gibanje ljudi v družbi, navigacija po svetovnem spletu ali pa nadzor v kompleksnih bioloških sistemih. Primere analize omrežij tako najdemo v biologiji, družbenih znanostih, ekonomiji, računalništvu in informatiki, ter še na številnih drugih področjih. Kljub zgornjemu pa je uporaba teorije omrežij še vedno v veliki meri omejena zgolj na akademske kroge. V prispevku zato predstavimo osnovne lastnosti velikih omrežij ter podamo nekatere zanimivejše primere uporabe.

Aljaž Zrnec, Dejan Lavbič, Lovro Šubelj, Slavko Žitnik, Aleš Kumer and Marko Bajec. 2012. Podatkovne baze NoSQL, Zbornik prispevkov 19. konference Dnevi slovenske informatike (DSI 2012), Portorož, Slovenia.
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Kratica NOSQL pomeni “Not Only SQL” in se jo pogosto povezuje z novo skupino podatkovnih baz, ki so se pojavile kot odgovor na težave, s katerimi se srečujemo pri uporabi relacijski baz podatkov. Za NOSQL podatkovne baze je težko podati natančno opredelitev, lahko pa trdimo, da zanje veljajo naslednje pomembne lastnosti: nimajo opredeljene sheme, prožnost, drobljenje, asinhrona replikacija, BASE pristop namesto ACID in arhitektura brez skupne rabe. Podatkovne baze NOSQL ne predstavljajo najboljše rešitve za reševanje vsakdanjih problemov povezanimi z upravljanjem s podatki. Nastale so na podlagi zahtev po visokih učinkovitosti in skalabilnosti v okolju kakršno je svetovni splet. Testirali smo več vrst NOSQL podatkovnih baz, ki se med seboj razlikujejo glede na namen uporabe. Za izbrane scenarije smo primerjali zmogljivosti ključvrednost podatkovne baze, podatkovne baze tipa razširljiv zapis in dokumentno usmerjene podatkovne baze. Rezultate smo primerjali tudi z zmogljivostmi klasične relacijske podatkovne baze MySQL. Na podlagi ugotovitev smo podali priporočila kdaj je smiselno uporabiti katero izmed naštetih rešitev.

2011 6x

Journal 2x

Aljaž Zrnec and Dejan Lavbič. 2011. Comparison of cloud vs. tape backup performance and costs with oracle database, Journal of Information and Organizational Sciences, 35(1), pp. 135–142.
PDF full text Journal link Publication link INSPEC COBISS Google Scholar (8 citations) bandwidth cloud computer center cost performance remote location service

Current practice of backing up data is based on using backup tapes and remote locations for storing data. Nowadays, with the advent of cloud computing a new concept of database backup emerges. The paper presents the possibility of making backup copies of data in the cloud. We are mainly focused on performance and economic issues of making backups in the cloud in comparison to traditional backups. We tested the performance and overall costs of making backup copies of data in Oracle database using Amazon S3 and EC2 cloud services. The costs estimation was performed on the basis of the prices published on Amazon S3 and Amazon EC2 sites.

Lovro Šubelj, David Jelenc, Eva Zupančič, Dejan Lavbič, Denis Trček, Marjan Krisper and Marko Bajec. 2011. Merging data sources based on semantics, contexts and trust, IPSI BgD Transactions on Internet Research, 7(1), pp. 18–30.
PDF full text COBISS Google Scholar (5 citations) entity resolution redundancy elimination semantic elevation context merging data trust management

Matching and merging of data from heterogeneous sources is a common need in various scenarios. Despite numerous algorithms proposed in the recent literature, there is a lack of general and complete solutions combining different dimensions arising during the matching and merging execution. We propose a general framework, and accompanying algorithms, that allow joint control over various dimensions of matching and merging. To achieve superior performance, standard (relational) data representation is enriched with semantics and thus elevated towards the real world situation. Data sources are merged using collective entity resolution and redundancy elimination algorithms that are managed through the use of different contexts – user, data and also trust contexts. Introduction of trust allows for an adequate trust management and efficient security assurance which is, besides a general solution for matching and merging, the main novelty of the proposition.

Conference 4x

Dejan Lavbič, Marjan Krisper and Marko Bajec. 2011. Continuous Evaluation in the process of Ontology Development, Proceedings of the 6th International conference on internet and web applications and services (ICIW 2011), 1st International workshop on enterprise cloud computing - strategies and solutions (ECCSS 2011), St. Maarten, Netherlands.
PDF full text COBISS WoS Google Scholar (1 citation)

Due to complexity of existing methodologies for ontology development we propose facilitating ontology development with continuous evaluation of steps in the process of ontology development. The approach is called Rapid Ontology Development (ROD) and is based on completeness indicator that helps guiding developer by constant evaluation of ontology and producing recommendations to progress to next step and improve the quality of ontology. The applicability of the approach is demonstrated on Financial Instruments and Trading Strategies (FITS) ontology. The main contribution of the paper is the suggested approach for rapid development of ontologies which brings ontology modeling closer to business users as it does not require from users to know any formal syntax.

Marko Bajec, Dejan Lavbič, Tomaž Vidonja and Andrej Kos. 2011. OCCAPI - odprta inteligentna komunikacijska platforma, Informatika v luči reforme javne uprave - zbornik konference Informatika v javni upravi 2011 (IJU 2011), Brdo pri Kranju, Slovenia.
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Dejan Lavbič and Marko Bajec. 2011. Rapid development of executable ontology for financial instruments and trading strategies, 2nd International Conference on Software Engineering and Computing Systems (ICSECS 2011), Software Engineering and Computer Systems, Part 1, Kuantan, Malaysia.
PDF full text Conference link Publication link INSPEC COBISS WoS Google Scholar (2 citations) financial instruments ontology rapid ontology development Semantic web trading strategies

In this paper we employ Rapid Ontology Development approach (ROD) with constant evaluation of steps in the process of ontology construction for development of Financial Instruments and Trading Strategies (FITS) ontology. We show that ontology development process does not conclude with successful definition of schematic part of ontology but we continue with post development activities where additional axiomatic information and instances with dynamic imports from various sources are defined. The result is executable ontology as part of Semantic Web application that uses data from several semi structured sources. The overall process of construction is suitable for users without extensive technical and programming skills and those users are rather experts in the problem domain.

Marko Bajec, Stefan Furlan, Aleš Kumer, Lovro Šubelj, Slavko Žitnik and Dejan Lavbič. 2011. Supervizor+, Informatika v luči reforme javne uprave - zbornik konference Informatika v javni upravi 2011 (IJU 2011), Brdo pri Kranju, Slovenia.
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2010 6x

Journal 3x

Dejan Lavbič, Iztok Lajovic and Marjan Krisper. 2010. Facilitating information system development with Panoramic view on data, Computer Science and Information Systems, 7(4), pp. 737–767.
HTML full text PDF full text Journal link Publication link arXiv link SCIE (Q₄) SCIE (Q₄) IF₂₀₁₀ = 0,324 COBISS WoS Google Scholar (13 citations) software development associative thinking object recognition rapid application development

The increasing amount of information and the absence of an effective tool for assisting users with minimal technical knowledge lead us to use associative thinking paradigm for implementation of a software solution - Panorama. In this study, we present object recognition process, based on context + focus information visualization techniques, as a foundation for realization of Panorama. We show that user can easily define data vocabulary of selected domain that is furthermore used as the application framework. The purpose of Panorama approach is to facilitate software development of certain problem domains by shortening the Software Development Life Cycle with minimizing the impact of implementation, review and maintenance phase. Our approach is focused on using and updating data vocabulary by users without extensive programming skills. Panorama therefore facilitates traversing through data by following associations where user does not need to be familiar with the query language, the data structure and does not need to know the problem domain fully. Our approach has been verified by detailed comparison to existing approaches and in an experiment by implementing selected use cases. The results confirmed that Panorama fits problem domains with emphasis on data oriented rather than ones with process oriented aspects. In such cases the development of selected problem domains is shortened up to 25%, where emphasis is mainly on analysis, logical design and testing, while omitting physical design and programming, which is performed automatically by Panorama tool.

Dejan Lavbič and Marjan Krisper. 2010. Facilitating Ontology Development with Continuous Evaluation, Informatica, 21(4), pp. 533–552.
HTML full text PDF full text Journal link Publication link arXiv link SCIE (Q₂) SCIE (Q₁) IF₂₀₁₀ = 1,786 COBISS WoS Google Scholar (15 citations) rapid ontology development Semantic web ontology completeness ontology development methodology ontology evaluation

In this paper we propose facilitating ontology development by constant evaluation of steps in the process of ontology development. Existing methodologies for ontology development are complex and they require technical knowledge that business users and developers don’t poses. By introducing ontology completeness indicator developer is guided throughout the development process and constantly aided by recommendations to progress to next step and improve the quality of ontology. In evaluating the ontology, several aspects are considered; from description, partition, consistency, redundancy and to anomaly. The applicability of the approach was demonstrated on Financial Instruments and Trading Strategies (FITS) ontology with comparison to other approaches.

Dejan Lavbič, Olegas Vasilecas and Rok Rupnik. 2010. Ontology-based multi-agent system to support business users and management, Technological and Economic Development of Economy, 16(2), pp. 327–347.
HTML full text PDF full text Journal link Publication link arXiv link SSCI (Q₁) IF₂₀₁₀ = 5,605 COBISS WoS Google Scholar (29 citations) Business Rules Agent Business Process Management Data Warehouse Decision support Information Retrieval Multi-Agent System Ontology

Abstract For some decision processes a significant added value is achieved when enterprises? internal Data Warehouse (DW) can be integrated and combined with external data gained from web sites of competitors and other relevant Web sources. In this paper we discuss the agent?based integration approach using ontologies (DSS?MAS). In this approach data from internal DW and external sources are scanned by coordinated group of agents, while semantically integrated and relevant data is reported to business users according to business rules. After data from internal DW, Web sources and business rules are acquired, agents using these data and rules can infer new knowledge and therefore facilitate decision making process. Knowledge represented in enterprises? ontologies is acquired from business users without extensive technical knowledge using user friendly user interface based on constraints and predefined templates. The approach presented in the paper was verified using the case study from the domain of mobile communications with the emphasis on supply and demand of mobile phones.

Conference 3x

Lovro Šubelj, Neli Blagus, Stefan Furlan, Bojan Klemenc, Aleš Kumer, Dejan Lavbič, Aljaž Zrnec, Slavko Žitnik and Marko Bajec. 2010. Analiza kompleksnih omrežij - osnovni pojmi in primeri uporabe v praksi, Informatika kot gonilo razvoja javne uprave - zbornik konference Informatika v javni upravi (IJU 2010), Brdo pri Kranju, Slovenia.
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Dejan Lavbič and Aljaž Zrnec. 2010. Ontology based agent system, Proceedings of the 2nd International conference on Information Society and Information Technologies (ISIT 2010), Novo mesto, Slovenia.
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Slavko Žitnik, Bojan Klemenc, Dejan Lavbič, Lovro Šubelj, Stefan Furlan, Aleš Kumer, Aljaž Zrnec, Neli Blagus and Marko Bajec. 2010. Trendi v inteligentnem pridobivanju podatkov iz heterogenih virov, Informatika kot gonilo razvoja javne uprave - zbornik konference Informatika v javni upravi (IJU 2010), Brdo pri Kranju, Slovenia.
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2009 2x

Journal 1x

Dejan Lavbič and Rok Rupnik. 2009. Multi-agent system for decision support in enterprises, Journal of Information and Organizational Sciences, 33(2), pp. 269–284.
PDF full text Journal link Publication link INSPEC COBISS Google Scholar (19 citations) ontology business rules data warehouse information retrieval intelligent agent

Business decisions must rely not only on organisation’s internal data but also on external data from competitors or relevant events. This information can be obtained from the Web but must be integrated with the data in an organisation’s Data Warehouse (DW). In this paper we discuss the agent-based integration approach using ontologies. To enable common understanding of a domain between people and application systems we introduce business rules approach towards ontology management. Because knowledge in organisation’s ontologies is acquired from business users without technical knowledge simple user interface based on ontology restrictions and predefined templates are used. After data from internal DW, Web and business rules are acquired; agent can deduce new knowledge and therefore facilitate decision making process. Tasks like information retrieval from competitors, creating and reviewing OLAP reports are autonomously performed by agents, while business users have control over their execution through knowledge base in ontology. The approach presented in the paper was verified on the case study from the domain of mobile communications with the emphasis on supply and demand of mobile phones and its accessories.

Conference 1x

Dejan Lavbič. 2009. Možnosti uporabe ontologij pri arhitekturi e-uprave, Povežimo informacijske otoke - zbornik konference Informatika v javni upravi (IJU 2009), Brdo pri Kranju, Slovenia.
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2008 2x

Journal 1x

Dejan Lavbič and Matjaž Gams. 2008. Agenti ali samo še en objektno usmerjen pristop?, Uporabna informatika, 16(3), pp. 162–170.
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Conference 1x

Dejan Lavbič and Marjan Krisper. 2008. Rapid ontology development model based on business rules management approach for the use in business applications, Proceedings of the 6th Doctoral Consortium on Enterprise Information Systems (DCEIS 2008) - In conjunction with 10th International Conference on Enterprise Information Systems (ICEIS 2008), Barcelona, Spain.
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Ontologies as means for knowledge manipulation in IT have gained its popularity in recent years. The scenarios of successful implementation can mainly be found in the World Wide Web domain and within academia while there are only a few in business environment. This paper introduces Rapid Ontologfy Development model and accompanying intelliOnto support tool to facilitate ontology construction for inclusion in business applications. Emphasis is given to simplification of the development process of functional components by bridging the gap between formal syntax of captured knowledge and acquisition of knowledge in semi formal way. Verification of the model will be presented with running examples from the domain of financial portfolio management and organisation of a rent-a-car etc.

2007 1x

Conference 1x

Dejan Lavbič, Rok Rupnik, Marko Bajec and Marjan Krisper. 2007. Agent oriented approach for integration of BI systems, Proceedings of 29th International Conference on Information Technology Interfaces (ITI 2007), Dubrovnik, Croatia.
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Decision Support in enterprises is gaining its importance in the age of Internet and e-business. While dealing with the need for fast response in the dynamic competitive environments and rapid increase of information available on various networks we propose Multi-Agent System approach to backend Decision Support. Research case study presented in the paper is from the domain of mobile communications with system’s main goal of delivering right information at the right time to the right users. We integrate several BI systems such as Data Mining and Data Warehousing with information available on the Internet. Ontologies are used to store derived knowledge, to support knowledge exchange between our MAS and other systems, to support agent-to-agent communication and enable seamless extending of MAS capabilities.

2006 5x

Journal 2x

Bogdan Kronovšek, Dejan Lavbič and Marjan Krisper. 2006. Mobilnost pri agentno usmerjenem razvoju programske opreme, Uporabna informatika, 14(4), pp. 182–195.
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Paradigma mobilnosti programske kode in inteligentnih agentov sta se zdruţili pri mobilnih agentih. Mobilni agenti so aktivne entitete, ki se selijo iz enega izvajalnega okolja v drugega, pri tem pa srečujejo druge agente, uporabljajo storitve in vire, ki so tam na voljo, medtem ko za poslovnega uporabnika izvršujejo določeno nalogo. Zaenkrat so še vedno bolj v domeni raziskovalnih krogov, kljub temu pa so obeti uporabe tega pristopa pri razvoju programske opreme veliki. Z razvojem kvalitetnih in zanesljivih platform, ki omogočajo implementacijo mobilnih agentov, se je zanimanje zanje zelo povečalo. Njihova uporabnost in prednosti pa se izkaţejo predvsem pri večjih omreţnih sistemih in internetu. Študija primera razvoja mobilnega agenta, ki ga prispevek predstavlja, je s področja poslovnega obveščanja, zdruţuje pa koncept mobilnih agentov in koncept mobilnega uporabnika.

Dejan Lavbič, Marko Bajec and Marjan Krisper. 2006. Pravila na semantičnem spletu, Elektrotehniški vestnik / Electrotechnical review, 73(5), pp. 249–254.
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Jeziki za predstavitev pravil imajo čedalje pomembnejšo vlogo pri uveljavljanju semantičnega spleta. Po eni strani pravila omogočajo zapis deklarativnega znanja pri jezikih za predstavitev ontologij in izražajo omejitve ali pretvorbe, ki so povezane z opisno logiko. Po drugi strani pa lahko s pravili opredelimo uveljavljanje politik, odzivanje na spremembe, specifikacijo delovanja inteligentnih agentov in jih uporabimo še za številne druge namene. Jeziki za predstavitev pravil bodo tako igrali ključno vlogo, saj bodo kot lingua franca za izmenjavo pravil med različnimi sistemi in orodji ter bodo omogočali razvijanje, izvajanje, objavljanje in medsebojno komunikacijo pravil na semantičnem spletu. V članku je predstavljeno ogrodje za predstavitev znanja na semantičnem spletu, kjer je poudarek na integraciji ontologij in pravil. Povezovanje je izpeljano s pomočjo pretvornikov, saj trenutno ni podpore za izvajanje pravil v obliki SWRL, ki je eden najobetavnejših predlogov pravil na semantičnem spletu.

Conference 3x

Dejan Lavbič and Viljan Mahnič. 2006. Intelligent agent aided use of unstructured information in decision support, Zbornik 9. mednarodne multikonference Informacijska družba (IS 2006), Ljubljana, Slovenia.
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Dejan Lavbič and Ana Bastinos Šaša. 2006. Knowledge management in multi-agent systems, Knowledge Management in Organizations - proocedings of the 1st International conference for new trends in Knowledge Management (KMO 2006), Maribor, Slovenia.
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Dejan Lavbič and Marjan Krisper. 2006. Semantične spletne storitve, V partnerstvu z informatiko do poslovne odličnosti - zbornik prispevkov 13. konference Dnevi slovenske informatike (DSI 2006), Portorož, Slovenia.
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2005 6x

Journal 1x

Dejan Lavbič and Marjan Krisper. 2005. Semantika podatkov in ontologije, Uporabna informatika, 13(3), pp. 121–135.
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Semantično strukturiranje, ki ga dosežemo z uporabo ontologij, se razlikuje od površinskega oblikovanja informacij, ki nam jih nudijo relacijske in XML podatkovne baze, saj mora biti pri podatkovnih bazah večina semantične vsebine zajete v uporabniških programih. Ontologije predstavljajo objektivno specifikacijo informacij za določeno domeno, kjer s predstavitvijo konceptov in medsebojnih relacij prikažemo znanje. Ta specifikacija je prvi korak pri gradnji naprednejših informacijskih sistemov, ki temeljijo na souporabi obstoječega znanja. V prispevku prikažemo stopnjo inteligence, ki so jo podatki skozi čas pridobivali, se ustavimo ter podrobneje opišemo najvišjo raven, ontologije in avtomatsko sklepanje. Predstavljen je opredelitev ontologij s filozofskega stališča in uporaba na področju računalništva in informatike, kjer omenimo jezike za opis in predstavitev ontologij.

Conference 5x

Dejan Lavbič, Rok Rupnik, Aljaž Zrnec, Damjan Vavpotič and Marjan Krisper. 2005. Agentno usmerjen razvoj informacijskih sistemov in večagentni sistemi, Informatika kot temelj povezovanja - zbornik prispevkov 12. konference Dnevi slovenske informatika (DSI 2005), Portorož, Slovenia.
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Dejan Lavbič. 2005. Avtonomna programska oprema in ponovna uporaba obstoječih informacij, Informatika kot temelj povezovanja - zbornik prispevkov 12. konference Dnevi slovenske informatika (DSI 2005), Portorož, Slovenia.
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Damjan Vavpotič, Marko Bajec, Marjan Krisper, Aljaž Zrnec and Dejan Lavbič. 2005. Merjenje in izboljševanje tehnične učinkovitosti in socialne sprejetosti metodologij razvoja IS, Informatika kot temelj povezovanja - zbornik prispevkov 12. konference Dnevi slovenske informatika (DSI 2005), Portorož, Slovenia.
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Dejan Lavbič, Rok Rupnik and Marjan Krisper. 2005. Poslovna pravila v večagentnih sistemih, Zbornik 8. mednarodne multikonference Informacijska družba (IS 2005), Ljubljana, Slovenia.
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Aljaž Zrnec, Marko Bajec, Marjan Krisper, Damjan Vavpotič, Dejan Lavbič and Marjan Krisper. 2005. Prilagajanje procesa konkretnim potrebam projekta, Informatika kot temelj povezovanja - zbornik prispevkov 12. konference Dnevi slovenske informatika (DSI 2005), Portorož, Slovenia.
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2004 1x

Conference 1x

Dejan Lavbič. 2004. Povezava rezultatov iskanja spletnega inteligentnega agenta s podatki pomembnimi za poslovne odločitve, Management in informatika - zbornik prispevkov 11. konference Dnevi slovenske informatike (DSI 2004), Portorož, Slovenia.
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