Iskanje po repozitoriju

Opis: Let Γ denote a finite, bipartite, connected graph with vertex set X. Fix x ∈ X and let ε ≥ 3 denote the eccentricity of x. For mutually distinct scalars {θ ∗ i }ε i=0 define a diagonal matrix A∗ = A∗(θ ∗ 0 , θ ∗ 1 , . . . , θ ∗ ε ) ∈ Mat X (R) as follows: for y ∈ X set (A∗)yy = θ ∗ ∂(x,y), where ∂ denotes the shortest path-length distance function of Γ. We say that A∗ is a dual adjacency matrix candidate of Γ with respect to x if the adjacency matrix A ∈ Mat X (R) of Γ and A∗ satisfy A3 A∗ − A∗ A3 + (β + 1)(A A∗ A2 − A2 A∗ A) = ρ(A A∗ − A∗ A) for some scalars β, ρ ∈ R. In this paper, we investigate when bipartite graphs that admit a dual adjacency matrix candidate also admit a uniform structure (in the sense of Terwilliger [6]). To do that, we first define a weakly uniform structure by slightly relaxing the conditions of uniform structure. The main result of this paper is that Γ admits a dual adjacency matrix candidate with respect to x if and only if Γ admits a weakly uniform structure with respect to x whose parameters satisfy some additional conditions. In particular, for β = 2, the weakly uniform structure is indeed a uniform structure.
Ključne besede: uniform property, dual adjacency matrix, Q-polynomial property
Objavljeno v RUP: 18.06.2026; Ogledov: 479; Prenosov: 10
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Opis: How long visitors spend viewing artworks, often referred to as dwell time, has long been studied in museology as a potential behavioral indicator of engagement. However, dwell time may encode both genuine preference and situational factors such as fatigue, and disentangling these signals for computational modeling has received limited attention. This study investigates whether dwell time can serve as a valid preference indicator for implicit user modeling and whether incorporating it can improve artwork recommendation. Using the BIRD dataset, which includes eye-tracking data for extracting dwell times and explicit preferences from 51 museum visitors, we report three main findings. First, visitors spend significantly longer (9.27 seconds on average) viewing artworks they like, with a large effect size (Cohen’s d = 1.47). Second, we confirm the museum fatigue phenomenon, the progressive decline in visitor attention throughout a visit, observing a 34% reduction in dwell time from visit start to end. Third, we evaluate collaborative filtering approaches and find that while purely implicit models using dwell time alone perform near-chance level, a hybrid approach that uses dwell time to compute item similarities while predicting preferences from explicit likes achieves the best performance (AUC-ROC = 0.755, AP = 0.522). These findings suggest that dwell time provides complementary information to explicit feedback and can enhance museum recommendation systems when appropriately integrated.
Ključne besede: implicit, user modeling, recommender systems, artwork, museum
Objavljeno v RUP: 09.06.2026; Ogledov: 563; Prenosov: 72
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Opis: Personalized news systems often adapt ranking to user preferences, which can reinforce selective exposure. We investigate an alterna- tive personalization strategy: stance-aware incentive shaping. In- stead of modifying content ranking, we use a minimal per-topic stance user model to adapt reward gradients, awarding more points for engaging with counter-attitudinal content. In a between-subject experiment (� = 98), we compare a non- adaptive baseline with two adaptive incentive framings (levels vs. leaderboards). Stance-aware gamification increased behavioral en- gagement (clicks and time), while subjective engagement and com- prehension did not differ reliably. Only the level-based framing produced significant pre–post increases in stance change and open- minded thinking, with effects varying by topic. We position stance-aware incentive shaping as a lightweight user-model intervention that adapts motivational feedback rather than ranking, offering an alternative pathway for diversity-aware personalization in recommender systems.
Ključne besede: information systems, recommender systems, personalization, human-centered computing, user studies
Objavljeno v RUP: 05.06.2026; Ogledov: 487; Prenosov: 12
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Opis: An (r, z; g)-mixed graph is a graph containing both edges and darts satisfying the regularity property that each vertex of the graph is incident to r edges, z ingoing and z outgoing darts (called total regularity), and being of oriented girth g, i.e., containing an oriented cycle of length g, and no shorter oriented cycles. The problem addressed in this paper is analogous to the Cage Problem and calls for determining the orders of the smallest totally regular (r, z; g)-mixed graphs. We derive several upper and lower bounds on the orders of such minimal graphs, study the relations between these extremal graphs and their non-oriented or digraphical counterparts, and focus on properties of totally regular mixed graphs obtained by replacing some of the edges of the incidence graphs of projective and biaffine planes by darts. We also introduce two constructions based on introducing additional edges or darts into induced subgraphs of these incidence graphs.
Ključne besede: totally regular mixed graph, girth, projective plane, biaffine plane
Objavljeno v RUP: 04.06.2026; Ogledov: 463; Prenosov: 25
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Opis: Aim Amphi–Adriatic–Ionian plant taxa, distributed on both the Balkan and Apennine peninsulas, exemplify one of the many diversity patterns characteristic of the Mediterranean biodiversity hotspot. To better understand these patterns, we examined the genetic and morphological variability, as well as the present day and Last Glacial Maximum (LGM) potential distribution of a scree-dwelling plant endemic to the study region. Location Amphi–Adriatic–Ionian region within the Mediterranean basin. Taxon Drypis spinosa L. (Caryophyllaceae). Methods Population genomics and phylogeographic patterns were investigated by analysing single–nucleotide polymorphisms (SNPs) and plastid DNA markers. Morphometric techniques were additionally used to assess taxonomic relationships. Environmental niche modelling (ENM) was applied to evaluate potential occurrences under present-day and LGM conditions. Results Genetic data revealed concordant patterns of genetic diversity, indicating that the mountainous areas of the western Balkans harbour the highest genetic variability in D. spinosa. Historical connections were detected among populations from the Kvarner area, the central and southern Apennines, and the Scardo–Pindic Mountains. Neither molecular nor morphological analyses supported the historically proposed lower-rank taxonomic distinctions. ENM suggests a substantial increase in favourable conditions during the LGM compared to the present day. Main Conclusions Our findings indicate two primary links between the Balkan Peninsula and the Apennines: one spanning the northern and central Adriatic Sea, involving populations from the Kvarner area and the central Dinaric Alps, and another connecting the Scardo–Pindic Mountains across the Ionian Sea. This reveals a biogeographical pattern not previously documented in plants with an Amphi–Adriatic–Ionian distribution.
Ključne besede: Amphi–Adriatic–Ionian distribution, environmental niche modelling, genomics, Mediterranean, morphometrics, phylogeography, plastid DNA
Objavljeno v RUP: 25.05.2026; Ogledov: 478; Prenosov: 11
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