Sanda Bujacic Babic

@math.uniri.hr

Faculty of Mathematics, University of Rijeka
Associate Professor

Sanda Bujacic Babic


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https://researchid.co/sbujacic
Dr Sanda Bujacic Babic, PhD - Faculty of Mathematics, University of Rijeka, Interests – Mathematical Modelling in Artificial Intelligence.
She is the course coordinator of the Machine Learning course at the Faculty of Mathematics and leads the project Mathematical Modelling in Natural Language Processing. Dr Bujacic Babic teaches courses that focus on problem solving, programme implementation for solving tasks in different programming languages and mathematical modelling. Her experience also extends to mentoring students, using both traditional and modern teaching methods, while providing some opportunities for applied mathematics by engaging with the real system in business. Dr Bujacic Babic’s contributions to the fields of mathematics and artificial intelligence are complemented by published papers and active participation in scientific communities.

RESEARCH, TEACHING, or OTHER INTERESTS

Algebra and Number Theory, Applied Mathematics, Theoretical Computer Science
10

Scopus Publications

62

Scholar Citations

4

Scholar h-index

3

Scholar i10-index

Scopus Publications

  • Graph-Based Lexical Sentiment Propagation Algorithm
    Tajana Ban Kirigin, Sanda Bujačić Babić, Benedikt Perak
    Mathematics, 2025
    In the rapidly developing field of sentiment analysis, it is a challenge to create sentiment dictionaries with broad coverage, especially for languages with limited resources. To address this problem, we propose innovative methodologies that automate the creation of comprehensive sentiment dictionaries, utilising both traditional linguistic approaches and state-of-the-art artificial intelligence technologies. The methodologies are characterised by their universal applicability to different languages. The proposed ConGraCNet Sentiment Propagation algorithm uniquely combines existing sentiment dictionaries and corpus-based syntactic–semantic embedding graphs to reliably capture and propagate sentiment values in lexical networks. To demonstrate the particular benefit for underrepresented languages with scarce sentiment resources, such as Croatian, we used the ConGraCNet Sentiment Propagation algorithm to create the Sentiment-hr dictionary and the AI tool GPT to generate the Sentiment-hr-AI dictionary. The two open-source sentiment dictionaries created are the largest and most comprehensive resources for the Croatian language to date, being at least ten times larger than the second-largest sentiment dictionary available. Our results demonstrate the effectiveness of the methods presented, which significantly expand the toolkit of sentiment analysis for the Croatian language and provide researchers with valuable insights and resources.
  • Semi-Local Integration Measure for Directed Graphs
    Tajana Ban Kirigin, Sanda Bujačić Babić
    Mathematics, 2024
    Directed and weighted graphs can be used for many real-world applications to model and analyse the quality and structure of communication within the system, the distribution and flow of information, and various resources, dependencies, resilience, etc. On social media platforms, for example, highly networked members, so-called influencers, disseminate information, opinions and trends to their followers, who in turn increase the popularity of the influencers through likes and comments. Both types of interaction have a major influence on discussions and activities in the social network. To identify the nodes with the highest integration and interconnectivity within the neighbourhood subnetwork, we introduce the Directed Semi-Local Integration (DSLI) centrality measure for directed and weighted graphs. This centrality measure evaluates the integration of nodes assessed by the presence of connection, the strength of links, the organisation and optimisation of inbound and outbound interconnectivity, and the redundancy in the local subnetwork, and provides a stronger differentiation of the importance of nodes than standard centrality measures. Thus, DSLI has the potential to be used for analysing the degree of integration for the uptake and dissemination of resources in complex networks in many different contexts.
  • POLYNOMIAL D(4)-QUADRUPLES OVER GAUSSIAN INTEGERS
    Marija Bliznac Trebješanin, Sanda Bujačić Babić, and
    Glasnik Matematicki, 2024
    A set \\(\\{a, b, c, d\\}\\) of four non-zero distinct polynomials in \\(\\mathbb{Z}[i][X]\\) is said to be a Diophantine \\(D(4)\\)-quadruple if the product of any two of its distinct elements increased by 4 is a square of some polynomial in \\(\\mathbb{Z}[i][X]\\). In this paper we prove that every \\(D(4)\\)-quadruple in \\(\\mathbb{Z}[i][X]\\) is regular, or equivalently that the equation \\[ (a+b-c-d)^2=(ab+4)(cd+4)\\hspace{20ex} \\] holds for every \\(D(4)\\)-quadruple in \\(\\mathbb{Z}[i][X]\\).
  • Graph-Based Taxonomic Semantic Class Labeling
    Tajana Ban Kirigin, Sanda Bujačić Babić, Benedikt Perak
    Future Internet, 2022
    We present a graph-based method for the lexical task of labeling senses of polysemous lexemes. The labeling task aims at generalizing sense features of a lexical item in a corpus using more abstract concepts. In this method, a coordination dependency-based lexical graph is first constructed with clusters of conceptually associated lexemes representing related senses and conceptual domains of a source lexeme. The label abstraction is based on the syntactic patterns of the x is_a y dependency relation. For each sense cluster, an additional lexical graph is constructed by extracting label candidates from a corpus and selecting the most prominent is_a collocates in the constructed label graph. The obtained label lexemes represent the sense abstraction of the cluster of conceptually associated lexemes. In a similar graph-based procedure, the semantic class representation is validated by constructing a WordNet hypernym relation graph. These additional labels indicate the most appropriate hypernym category of a lexical sense community. The proposed labeling method extracts hierarchically abstract conceptual content and the sense semantic features of the polysemous source lexeme, which can facilitate lexical understanding and build corpus-based taxonomies.
  • Semi-Local Integration Measure of Node Importance
    Tajana Ban Kirigin, Sanda Bujačić Babić, Benedikt Perak
    Mathematics, 2022
    Numerous centrality measures have been introduced as tools to determine the importance of nodes in complex networks, reflecting various network properties, including connectivity, survivability, and robustness. In this paper, we introduce Semi-Local Integration (SLI), a node centrality measure for undirected and weighted graphs that takes into account the coherence of the locally connected subnetwork and evaluates the integration of nodes within their neighbourhood. We illustrate SLI node importance differentiation among nodes in lexical networks and demonstrate its potential in natural language processing (NLP). In the NLP task of sense identification and sense structure analysis, the SLI centrality measure evaluates node integration and provides the necessary local resolution by differentiating the importance of nodes to a greater extent than standard centrality measures. This provides the relevant topological information about different subnetworks based on relatively local information, revealing the more complex sense structure. In addition, we show how the SLI measure can improve the results of sentiment analysis. The SLI measure has the potential to be used in various types of complex networks in different research areas.
  • Lexical sense labeling and sentiment potential analysis using corpus-based dependency graph
    Tajana Ban Kirigin, Sanda Bujačić Babić, Benedikt Perak
    Mathematics, 2021
    This paper describes a graph method for labeling word senses and identifying lexical sentiment potential by integrating the corpus-based syntactic-semantic dependency graph layer, lexical semantic and sentiment dictionaries. The method, implemented as ConGraCNet application on different languages and corpora, projects a semantic function onto a particular syntactical dependency layer and constructs a seed lexeme graph with collocates of high conceptual similarity. The seed lexeme graph is clustered into subgraphs that reveal the polysemous semantic nature of a lexeme in a corpus. The construction of the WordNet hypernym graph provides a set of synset labels that generalize the senses for each lexical cluster. By integrating sentiment dictionaries, we introduce graph propagation methods for sentiment analysis. Original dictionary sentiment values are integrated into ConGraCNet lexical graph to compute sentiment values of node lexemes and lexical clusters, and identify the sentiment potential of lexemes with respect to a corpus. The method can be used to resolve sparseness of sentiment dictionaries and enrich the sentiment evaluation of lexical structures in sentiment dictionaries by revealing the relative sentiment potential of polysemous lexemes with respect to a specific corpus. The proposed approach has the potential to be used as a complementary method to other NLP resources and tasks, including word disambiguation, domain relatedness, sense structure, metaphoricity, as well as a cross- and intra-cultural discourse variations of prototypical conceptualization patterns and knowledge representations.
  • On some diophantine equations
    S. Bujacic Babic, K. Nabardi
    Miskolc Mathematical Notes, 2021
    In this paper we deal with some Diophantine equations and present infinitely many positive integer solutions for each one of them. 2010 Mathematics Subject Classification: 11D45; 11D25
  • Two divisors of (n2 + 1)/2 summing up to δn + δ ± 2, δ even
    Sanda Bujačić Babić
    Rad Hrvatske Akademije Znanosti I Umjetnosti Matematicke Znanosti, 2018
  • A variation of a congruence of Subbarao for n= 2 α5 β
    Sanda Bujačić
    Periodica Mathematica Hungarica, 2017
  • Two divisors of (n2 +1)/2 summing up to δn + ε, for δ and ε even
    Sanda Bujačić
    Miskolc Mathematical Notes, 2014
    In this paper we are dealing with the problem of the existence of two divisors of $(n^2+1)/2$ whose sum is equal to $\\delta n+\\varepsilon$, in the case when $\\delta$ and $\\varepsilon$ are even, or more precisely in the case in which $\\delta\\equiv\\varepsilon+2\\equiv0$ or $2 \\pmod{4}$. We will completely solve the cases $\\delta=2, \\delta=4$ and $\\varepsilon=0$.

RECENT SCHOLAR PUBLICATIONS

  • Interpretable vs. Learnable Centrality: Combining SLI and Neural Networks
    SB Babic, TB Kirigin
    Logic and Applications LAP 2025, 15 , 2025
    2025
  • Graph-Based Lexical Sentiment Propagation Algorithm.
    T Ban Kirigin, S Bujačić Babić, B Perak
    Mathematics, MDPI 13, https://doi.org/10.3390/math13071141 , 2025
    2025
    Citations: 1
  • Measuring Node Integration in Directed Graphs and the Applications
    SB Babic, TB Kirigin
    Logic and Applications LAP 2024, 16 , 2024
    2024
  • Polynomial -quadruples over Gaussian integers
    MB Trebješanin, SB Babić
    Glasnik matematički 59 (1), 1-31 , 2024
    2024
    Citations: 1
  • Semi-Local Integration Measure for Directed Graphs
    T Ban Kirigin, S Bujačić Babić
    Mathematics 12 (7), 1087 , 2024
    2024
    Citations: 3
  • Graph Based Sentiment Propagation Algorithm
    TB Kirigin, SB Babic, B Perak
    Logic and Applications LAP 2023, 7 , 2023
    2023
  • Graph Based Sentiment Propagation Algorithm
    T Ban Kirigin, S Bujačić Babić, B Perak
    Logic and Applications: Book of Abstracts, 7-8 , 2023
    2023
  • Graph-based taxonomic semantic class labeling
    T Ban Kirigin, S Bujačić Babić, B Perak
    Future Internet 14 (12), 383 , 2022
    2022
    Citations: 4
  • Semi-local integration measure of node importance
    T Ban Kirigin, S Bujačić Babić, B Perak
    Mathematics 10 (3), 405 , 2022
    2022
    Citations: 14
  • On the regularity of the D (4)-quadruples in Z [i][X]
    S Bujačić Babić
    Conference on Diophantine m-tuples and related problems III, 9-10 , 2022
    2022
  • Polynomial D (4)-quadruples over Gaussian integers
    S Bujačić Babić, M Bliznac Trebješanin
    SEDMI HRVATSKI MATEMATIČKI KONGRES, 9-9 , 2022
    2022
  • Semi-Local Integration Centrality for Complex Networks
    T Ban Kirigin, S Bujačić Babić, B Perak
    Book of Abstracts LAP 2022, 58-59 , 2022
    2022
  • Syntactic Dependency Networks: Cognitive Aspects of Hierarhical Multi-Layer Structures
    T Ban Kirigin, S Bujačić Babić, B Perak
    Book of Abstracts LAP 2022, 60-61 , 2022
    2022
  • Semi-Local Integration Centrality for Complex Networks
    TB Kirigin, SB Babic, B Perak
    Logic and Applications LAP 2022, 58 , 2021
    2021
  • Implementing Sentiment Dictionary into Vader sentiment analyis for Croatian
    TB Kirigin, SB Babic, B Perak
    Logic and Applications LAP 2021, 69 , 2021
    2021
    Citations: 1
  • Building a Sentiment Dictionary for Croatian
    TB Kirigin, SB Babic, B Perak
    Logic and Applications LAP 2021, 67 , 2021
    2021
  • Lexical sense labeling and sentiment potential analysis using corpus-based dependency graph
    T Ban Kirigin, S Bujačić Babić, B Perak
    Mathematics 9 (12), 1449 , 2021
    2021
    Citations: 17
  • Sentiment Potential Analysis
    T Ban Kirigin, S Bujačić Babić, B Perak
    Book of Abstracts LAP 2021, 64-66 , 2021
    2021
  • Building a Sentiment Dictionary for Croatian
    T Ban Kirigin, S Bujačić Babić, B Perak
    Logic and Applications 2021, 67-68 , 2021
    2021
  • On some Diophantine equations
    SB Babic, K Nabardi
    Miskolc mathematical notes 22 (1), 65-75 , 2021
    2021
    Citations: 2

MOST CITED SCHOLAR PUBLICATIONS

  • Lexical sense labeling and sentiment potential analysis using corpus-based dependency graph
    T Ban Kirigin, S Bujačić Babić, B Perak
    Mathematics 9 (12), 1449 , 2021
    2021
    Citations: 17
  • Semi-local integration measure of node importance
    T Ban Kirigin, S Bujačić Babić, B Perak
    Mathematics 10 (3), 405 , 2022
    2022
    Citations: 14
  • Linear forms in logarithms
    S Bujačić, A Filipin
    Diophantine Analysis: Course Notes from a Summer School, 1-59 , 2016
    2016
    Citations: 13
  • Graph-based taxonomic semantic class labeling
    T Ban Kirigin, S Bujačić Babić, B Perak
    Future Internet 14 (12), 383 , 2022
    2022
    Citations: 4
  • Diophantine analysis: course notes from a summer school
    S Bujačić, A Filipin, S Kristensen, T Matala-aho, NMR Oswald
    Birkhäuser , 2016
    2016
    Citations: 4
  • Semi-Local Integration Measure for Directed Graphs
    T Ban Kirigin, S Bujačić Babić
    Mathematics 12 (7), 1087 , 2024
    2024
    Citations: 3
  • On some Diophantine equations
    SB Babic, K Nabardi
    Miskolc mathematical notes 22 (1), 65-75 , 2021
    2021
    Citations: 2
  • Two divisors of (n^ 2+ 1)/2 summing up to {\delta} n+ {\epsilon}, for {\delta} and {\epsilon} even
    S Bujačić
    Miskolc Mathematical Notes 15 (2), 333-344 , 2014
    2014
    Citations: 2
  • Graph-Based Lexical Sentiment Propagation Algorithm.
    T Ban Kirigin, S Bujačić Babić, B Perak
    Mathematics, MDPI 13, https://doi.org/10.3390/math13071141 , 2025
    2025
    Citations: 1
  • Polynomial -quadruples over Gaussian integers
    MB Trebješanin, SB Babić
    Glasnik matematički 59 (1), 1-31 , 2024
    2024
    Citations: 1
  • Implementing Sentiment Dictionary into Vader sentiment analyis for Croatian
    TB Kirigin, SB Babic, B Perak
    Logic and Applications LAP 2021, 69 , 2021
    2021
    Citations: 1
  • Interpretable vs. Learnable Centrality: Combining SLI and Neural Networks
    SB Babic, TB Kirigin
    Logic and Applications LAP 2025, 15 , 2025
    2025
  • Measuring Node Integration in Directed Graphs and the Applications
    SB Babic, TB Kirigin
    Logic and Applications LAP 2024, 16 , 2024
    2024
  • Graph Based Sentiment Propagation Algorithm
    TB Kirigin, SB Babic, B Perak
    Logic and Applications LAP 2023, 7 , 2023
    2023
  • Graph Based Sentiment Propagation Algorithm
    T Ban Kirigin, S Bujačić Babić, B Perak
    Logic and Applications: Book of Abstracts, 7-8 , 2023
    2023
  • On the regularity of the D (4)-quadruples in Z [i][X]
    S Bujačić Babić
    Conference on Diophantine m-tuples and related problems III, 9-10 , 2022
    2022
  • Polynomial D (4)-quadruples over Gaussian integers
    S Bujačić Babić, M Bliznac Trebješanin
    SEDMI HRVATSKI MATEMATIČKI KONGRES, 9-9 , 2022
    2022
  • Semi-Local Integration Centrality for Complex Networks
    T Ban Kirigin, S Bujačić Babić, B Perak
    Book of Abstracts LAP 2022, 58-59 , 2022
    2022
  • Syntactic Dependency Networks: Cognitive Aspects of Hierarhical Multi-Layer Structures
    T Ban Kirigin, S Bujačić Babić, B Perak
    Book of Abstracts LAP 2022, 60-61 , 2022
    2022
  • Semi-Local Integration Centrality for Complex Networks
    TB Kirigin, SB Babic, B Perak
    Logic and Applications LAP 2022, 58 , 2021
    2021

Publications

Tajana Ban Kirigin, Sanda Bujačić Babić, Benedikt Perak, Graph-Based Taxonomic Semantic Class Labeling Future Internet 2022 - 14 (12),

Ban Kirigin, Tajana; Bujačić Babić, Sanda; Perak, Benedikt, Semi-Local Integration Measure of Node Importance, Mathematics, 10(3), (2022), 405; - 10 1-16,

Ban Kirigin, Tajana; Bujačić Babić, Sanda; Perak, Benedikt, Lexical Sense Labeling and Sentiment Potential Analysis using Corpus-Based Dependency Graph, Mathematics, 9(12), (2021), 1449; 1-22 - 9 1-22,

Bujačić Babić, Sanda, Nabardi, Kamran, On Some Diophantine Equations, Miskolc Mathematical Notes - 1-11,

Bujačić, Sanda, Two divisors of (n^2+1)/2 summing up to δn + δ ± 2, δ even, Rad Hrvatske akademije znanosti i umjetnosti. Razred za matematičke, fizičke i kemijske znanosti. Matematičke znanosti - 22 39 - 61,

Bujačić, Sanda, A variation of a congruence of Subbarao for n=2^α*5^β, α, β>=0, Periodica Mathematica Hungarica - 75 66 - 79,

S. Bujačić, A. Filipin, Linear Forms in Logarithms, Springer-Verlag, Berlin, Jörn Steuding editor - 1-59

Bujačić, Sanda, Two divisors of (n^2+1)/2 summing up to δn+ε, for δ and ε even, Miskolc Mathematical Notes - 15 333-344,