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1112. Charge density study of two-electron four-center bonding in a dimer of tetracyanoethylene radical anions as a benchmark for two-electron multicenter bondingMiha Virant, Petar Štrbac, Anna Krawczuk, Valentina Milašinović, Petra Stanić, Matic Lozinšek, Krešimir Molčanov, 2024, original scientific article Abstract: The dimer of the tetracyanoethylene (TCNE) radical anions represents the simplest and the best studied case of two-electron multicenter covalent bonding (2e/mc or pancake bonding). The model compound, N-methylpyridinium salt of TCNE•–, is diamagnetic, meaning that the electrons in two contiguous radicals are paired and occupy a HOMO orbital which spans two TCNE•– radicals. Charge density in this system is studied as a benchmark for comparison of charge densities in other pancake-bonded radical systems. Two electrons from two contiguous radicals indeed form a bonding electron pair, which is distributed between two central ethylene groups in the dimer, i.e., between four carbon atoms. The topology of electron density reveals two bond critical points between the central ethylene groups in the dimer, with maximum electron density of 0.185 e Å–3; the corresponding theoretical value is 0.118 e Å–3.
Published in DiRROS: 09.09.2025; Views: 281; Downloads: 59
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1115. Automated grading through contrastive learning : a gradient analysis and feature ablation approachMateo Sokač, Mario Fabijanić, Igor Mekterović, Leo Mršić, 2025, original scientific article Abstract: As programming education becomes increasingly complex, grading student code has become a challenging task. Traditional methods, such as dynamic and static analysis, offer foundational approaches but often fail to provide granular insights, leading to inconsistencies in grading and feedback. This study addresses the limitations of these methods by integrating contrastive learning with explainable AI techniques to assess SQL code submissions. We employed contrastive learning to differentiate between student and correct SQL solutions, projecting them into a high-dimensional latent space, and used the Frobenius norm to measure the distance between these representations. This distance was used to predict the percentage of points deducted from each student’s solution. To enhance interpretability, we implemented feature ablation and integrated gradients, which provide insights into the specific tokens in student code that impact the grading outcomes. Our findings indicate that this approach improves the accuracy, consistency, and transparency of automated grading, aligning more closely with human grading standards. The results suggest that this framework could be a valuable tool for automated programming assessment systems, offering clear, actionable feedback and making machine learning models in educational contexts more interpretable and effective.
Keywords: automated programming assessment systems (APASs), contrastive learning, explainable AI, feature ablation, integrated gradients, machine learning in education, natural language processing (NLP)
Published in DiRROS: 09.09.2025; Views: 304; Downloads: 151
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1118. Strength prominence index : a link prediction method in fuzzy social networkSakshi Dev Pandey, Sovan Samanta, Leo Mršić, Antonios Kalampakas, Tofigh Allahviranloo, 2025, original scientific article Abstract: Link prediction is a field within social network studies that aims to forecast future connections based on the structure of a social network. This paper introduces a link prediction method based on the strength and prominence of seed node pairs, referred to as the strength prominence index. In this method, we get a consistent score for any pair of nodes, regardless of whether they share a common neighbour. Several key characteristics have been identified. In our experiments, we used three well-known estimators to evaluate the accuracy of link prediction algorithms: precision, area under the precision-recall curve, and area under the receiver operating characteristic curve. A comparative study with existing methods is also presented, supported by relevant graphs and tables. Validation using Facebook data sets demonstrates the effectiveness of the proposed method.
Keywords: link prediction, similarity indices, fuzzy social network, strength prominence (SP) index
Published in DiRROS: 09.09.2025; Views: 296; Downloads: 80
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1120. A mesoionic bis(Py-tzNHC) palladium(II) complex catalyses "green" Sonogashira reaction through an unprecedented mechanismMartin Gazvoda, Miha Virant, Andrej Pevec, Damijana Urankar, Aljoša Bolje, Marijan Kočevar, Janez Košmrlj, 2016, original scientific article Keywords: catalysis, palladium, ligand, carbene, Sonogashira, mechanism, mass spectrometry
Published in DiRROS: 09.09.2025; Views: 250; Downloads: 123
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