Ab initio informed 20Ne(p, pα)16O reaction elucidates the emergence of alpha clustering from chiral potentials
Autoři
Sargsyan, G.H.; Yoshida, K.; Ogata, K.; Launey, K.D.; Escher, J.E.; Langr, D.; Dytrych, T.
Rok
2025
Publikováno
Physics Letters B. 2025, 866 1-6. ISSN 0370-2693.
Typ
Článek
Anotace
We report on the first ab initio informed α knock-out reaction in the intermediate-mass region, with the aim to probe the underlying chiral potential and its impact on the emergence of alpha clustering in this mass region. The theoretical predictions of the α+16O clustering in the 20Ne ground state, based on the ab initio symmetry-adapted no-core shell model with continuum, yield a triple differential cross section for 20Ne(p, pα)16O that is in a remarkable agreement with the data. This allows us to examine predictions of surface and in-medium α-cluster features that emerge from the underlying realistic nucleon-nucleon interaction with no parameters fitted to nuclear data beyond the two-body system, and to compare these to the successful antisymmetrized molecular dynamics approach.
Accessible Hardware Implementation for Multi-Agent Collective Construction
Autoři
Rameš, M.; Surynek, P.
Rok
2025
Publikováno
Proceedings of the 39th AAAI Conference on Artificial Intelligence. Menlo Park: AAAI Press, 2025. p. 29688-29690. ISSN 2159-5399.
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Anotace
We propose a 2D simulation system for multi-agent collective construction (MACC) based on simple line-following intelligent machines (SLIM) - small differential drive mobile robots. Our MACC-SLIM system alleviates the high upfront cost of implementing MACC on real hardware. Our system builds upon widely available resources, namely a standard LCD screen and commodity mobile robots, allowing researchers and schools easier access to MACC hardware implementation. We test the system on plans generated by an optimal state-of-the-art MACC algorithm, demonstrating there are still non-insignificant synchronization delays. The MACC-SLIM system allows us to observe bottlenecks, parallelism, and possible execution failures of plans generated by the MACC algorithms.
Additive structure of non-monogenic simplest cubic fields
Autoři
Gil-Muñoz, D.; Tinková, M.
Rok
2025
Publikováno
The Ramanujan Journal. 2025, 66(3), ISSN 1382-4090.
Typ
Článek
Anotace
We consider Shanks’ simplest cubic fields K for which the index [O_K : Z[rho]] of a root rho of the defining parametric polynomial is 3. For them, we study the additive indecomposables of K and provide a complete list of them. Moreover, we use the knowledge of the indecomposables to prove some interesting consequences on the arithmetic of K. Mainly, we obtain good bounds on the ranks of universal quadratic forms over K and prove that the Pythagoras number of O_K is 6.
Algebraic Characterization of Dendricity
Autoři
Gheeraert, F.; Goulet-Ouellet, H.; Leroy, J.; Stas, P.
Rok
2025
Publikováno
The Electronic Journal of Combinatorics. 2025, 32(1), 1-8. ISSN 1077-8926.
Typ
Článek
DOI
Anotace
Dendric shift spaces simultaneously generalize co dings of regular interval exchanges and episturmian shift spaces, themselves both generalizations of Sturmian words. One of the key properties enforced by dendricity is the Return Theorem. In this paper, we prove its converse, providing the following natural algebraic perspective on dendricity: A minimal shift space is dendric if and only if every set of return words is a basis of the free group over the alphabet.
Anomaly Detection in Log Streams based on Time-Contextual Models
Autoři
Fedotov, D.; Kuchař, J.; Vitvar, T.
Rok
2025
Publikováno
Web Information Systems Engineering – WISE 2024. Springer Nature Singapore Pte Ltd., 2025. p. 19-29. 1. ISSN 0302-9743. ISBN 978-981-96-0575-0.
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Stať ve sborníku
Anotace
Organisations today heavily rely on complex software systems integrated through multiple layers of middleware. This complexity leads to substantial generation of operational data of structured and semi-structured formats which is recorded in log files. The workload of the system fluctuates according to specific periods of the day which impacts the amount and quality of data generated in log files. In this paper, we propose a new log anomaly detection approach that leverages a collection of smaller models designed to capture workload fluctuations over specific time intervals. We demonstrate its effectiveness in detecting anomalies within log streams. Our evaluation uses log data from servers in a production environment, handling a complex back-end system that processes hundreds of requests per second. We show that our method outperforms traditional and widely used anomaly detection methods in data streams in the context of dynamic and time-sensitive workload scenarios.
Arithmetic of cubic number fields: Jacobi–Perron, Pythagoras, and indecomposables
Autoři
Kala, V.; Sgallová, E.; Tinková, M.
Rok
2025
Publikováno
Journal of Number Theory. 2025, 273 37-95. ISSN 0022-314X.
Typ
Článek
Anotace
We study a new connection between multidimensional continued fractions, such as Jacobi-Perron algorithm, and additively indecomposable integers in totally real cubic number fields. First, we find the indecomposables of all signatures in Ennola's family of cubic fields, and use them to determine the Pythagoras numbers. Second, we compute a number of periodic JPA expansions, also in Shanks' family of simplest cubic fields. Finally, we compare these expansions with indecomposables to formulate our conclusions.
Balanced and Fair Partitioning of Friends
Autoři
Deligkas, A.; Eiben, E.; Ioannidis, S.D.; Knop, D.; Schierreich, Š.
Rok
2025
Publikováno
Proceedings of the 39th AAAI Conference on Artificial Intelligence. Menlo Park: AAAI Press, 2025. p. 13754-13762. ISSN 2159-5399.
Typ
Stať ve sborníku
Anotace
In the recently introduced model of fair partitioning of friends, there is a set of agents located on the vertices of an underlying graph that indicates the friendships between the agents. The task is to partition the graph into k balanced-sized groups, keeping in mind that the value of an agent for a group is equal to the number of edges they have in that group. The goal is to construct partitions that are "fair", i.e., no agent would like to replace an agent in a different group. We generalize the standard model by considering utilities for the agents that are beyond binary and additive. Having this as our foundation, our contribution is threefold:
(a) we adapt several fairness notions that have been developed in the fair division literature to our setting;
(b) we give several existence guarantees supported by polynomial-time algorithms;
(c) we initiate the study of the computational (and parameterized) complexity of the model and provide an almost complete landscape of the (in)tractability frontier for our fairness concepts.
CESNET-TimeSeries24: Time Series Dataset for Network Traffic Anomaly Detection and Forecasting
Autoři
Rok
2025
Publikováno
Scientific Data. 2025, 12(1), ISSN 2052-4463.
Typ
Článek
Anotace
Anomaly detection in network traffic is crucial for maintaining the security of computer networks and identifying malicious activities. Most approaches to anomaly detection use methods based on forecasting. Extensive real-world network datasets for forecasting and anomaly detection techniques are missing, potentially causing overestimation of anomaly detection algorithm performance and fabricating the illusion of progress. This manuscript tackles this issue by introducing a comprehensive dataset derived from 40 weeks of traffic transmitted by 275,000 active IP addresses in the CESNET3 network—an ISP network serving approximately half a million customers daily. It captures the behavior of diverse network entities, reflecting the variability typical of an ISP environment. This variability provides a realistic and challenging environment for developing forecasting and anomaly detection models, enabling evaluations that are closer to real-world deployment scenarios. It provides valuable insights into the practical deployment of forecast-based anomaly detection approaches.
Combining Type Inference Techniques for Semi-Automatic UML Generation from Pharo Code
Autoři
Rok
2025
Publikováno
Journal of Computer Languages. 2025, 82 ISSN 2590-1184.
Typ
Článek
Anotace
This paper explores how to reconstruct UML diagrams from dynamically typed languages such as Smalltalk, which do not use explicit type information. This lack of information makes traditional methods for extracting associations difficult.
It addresses the need for automated techniques, particularly in legacy software systems, to facilitate their transformation into modern technologies, focusing on Smalltalk as a case study due to its extensive industrial legacy and modern adaptations like Pharo.
We propose a way to create UML diagrams from Smalltalk code, focusing on using type inference to determine UML associations. For optimal outcomes for large-scale software systems, we recommend combining different type inference methods in an automatic or semi-automatic way.
Context-Aware REpresentation: Jointly Learning Item Features and Selection From Triplets
Autoři
da Silva Alves, R.; Ledent, A.
Rok
2025
Publikováno
IEEE Transactions on Neural Networks and Learning Systems. 2025, 36(4), 6492-6502. ISSN 2162-237X.
Typ
Článek
Anotace
In areas of machine learning such as cognitive modeling or recommendation, user feedback is usually context-dependent. For instance, a website might provide a user with a set of recommendations and observe which (if any) of the links were clicked by the user. Similarly, there is growing interest in the so-called “odd-one-out” learning setting, where human participants are provided with a basket of items and asked which is the most dissimilar to the others. In both of those cases, the presence of all the items in the basket can influence the final decision. In this article, we consider a classification task where each input consists of three items (a triplet), and the task is to predict which of the three will be selected. Our aim is not only to return accurate predictions for the selection task, but also to additionally provide interpretable feature representations for both the context and for each individual item. To achieve this, we introduce CARE, a specialized neural network architecture that yields Context-Aware REpresentations of items based on observations of triplets of items alone. We demonstrate that, in addition to achieving state-of-the-art performance at the selection task, our model can produce meaningful representations both for each item, as well for each context (triplet of items). This is done using only triplet responses: CARE has no access to supervised item-level information. In addition, we prove parameter counting generalization bounds for our model in the i.i.d. setting, demonstrating that the apparent sample sparsity arising from the combinatorially large number of possible triplets is no obstacle to efficient learning.
Controllability-Based Circuit Similarity Estimation
Autoři
Žáček, M.; Fišer, P.
Rok
2025
Publikováno
Proceedings of the 28th International Symposium on Design and Diagnostics of Electronic Circuits & Systems. Piscataway: IEEE, 2025. p. 127-130. ISBN 979-8-3315-2801-0.
Typ
Stať ve sborníku
Anotace
Assessing the structural similarity of different implementations of logic functions is of importance in many areas of digital design, such as iterative resynthesis, engineering change order (ECO) based design, design of reliable redundant systems (duplex, TMR), etc. In general, numerous metrics exist that describe such similarity, mostly based on its intended application. In this paper, we introduce a novel metric based on a calculation of the functional equivalence of subcircuits. As this approach requires repeated calls of time-consuming functional equivalence checking, we propose a linear-time approximation of this method based on signal controllability calculation.
These two approaches are compared to the state-of-the-art fault detection-based design diversity estimation technique and applied to assess the fault-security capabilities of duplex systems.
Counting circuit double covers
Autoři
Hušek, R.; Šámal, R.
Rok
2025
Publikováno
Journal of Graph Theory. 2025, 108(2), 374-395. ISSN 0364-9024.
Typ
Článek
Anotace
We study a counting version of Cycle Double Cover Conjecture. We discuss why it is more interesting to count circuits (i.e., graphs isomorphic to C_k for some k) instead of cycles (graphs with all degrees even). We give an almost-exponential lower bound for graphs with a surface embedding of representativity at least 4. We also prove an exponential lower bound for planar graphs. We conjecture that any bridgeless cubic graph has at least 2^(n/2 - 1) circuit double covers and we show an infinite class of graphs for which this bound is tight.
Efficient Algorithm for U(N) to U(3) Representation Reduction in Isospin-Adapted Nuclear Structure Calculations
Autoři
Langr, D.; Dytrych, T.
Rok
2025
Publikováno
Parallel Processing and Applied Mathematics Part III. Basel: Springer Nature Switzerland AG, 2025. p. 233-243. Lecture Notes in Computer Science. vol. 15581. ISSN 0302-9743. ISBN 978-3-031-85702-7.
Typ
Stať ve sborníku
Anotace
An efficient algorithm for enumerating representations of the unitary group U(3) that occur in a representation of the unitary group U(N) is introduced. The algorithm is applicable to U(N) representations associated with a system of nucleons distributed among the degenerate eigenstates of the selected three-dimensional harmonic oscillator level, where each eigenstate can be occupied by up to 4 particles with different combinations of spin and isospin quantum numbers. A C++ implementation of the proposed algorithm is provided, and its performance evaluation is reported.
Exact Algorithms and Lower Bounds for Forming Coalitions of Constrained Maximum Size
Autoři
Fioravantes, F.; Gahlawat, H.; Melissinos, N.
Rok
2025
Publikováno
Proceedings of the 39th AAAI Conference on Artificial Intelligence. Menlo Park: AAAI Press, 2025. ISSN 2159-5399.
Typ
Stať ve sborníku
Anotace
Imagine we want to split a group of agents into teams in the most efficient way, considering that each agent has their own preferences about their teammates. This scenario is modeled by the extensively studied Coalition Formation problem. Here, we study a version of this problem where each team must additionally be of bounded size.
We conduct a systematic algorithmic study, providing several intractability results as well as multiple exact algorithms that scale well as the input grows (FPT), which could prove useful in practice.
Our main contribution is an algorithm that deals efficiently with tree-like structures (bounded treewidth) for "small" teams. We complement this result by proving that our algorithm is asymptotically optimal. Particularly, there can be no algorithm that vastly outperforms the one we present, under reasonable theoretical assumptions, even when considering star-like structures (bounded vertex cover number).
Failures of integral Springer's theorem
Autoři
Daans, N.; Kala, V.; Krásenský, J.; Yatsyna, P.
Rok
2025
Publikováno
Proceedings of the American Mathematical Society. 2025, 153(6), 2369-2379. ISSN 0002-9939.
Typ
Článek
Anotace
We discuss the phenomenon where an element in a number field is not integrally represented by a given positive definite quadratic form, but becomes integrally represented by this form over a totally real extension of odd degree. We prove that this phenomenon happens infinitely often, and, conversely, establish finiteness results about the situation when the quadratic form is fixed.
Kernel Estimates of Pedestrian Density Applied in Simulation of Recreational Pedestrian Movement
Autoři
Novotný, T.; Vacková, J.; Hrabák, P.
Rok
2025
Publikováno
Parallel Processing and Applied Mathematics Part III. Basel: Springer Nature Switzerland AG, 2025. p. 328-344. Lecture Notes in Computer Science. vol. 15581. ISSN 0302-9743. ISBN 978-3-031-85702-7.
Typ
Stať ve sborníku
Anotace
A model for simulating pedestrian recreational movement along a tourist trail is introduced. The model reduces the two-dimensional nature of bidirectional flow to one dimension while preserving the inter-agent interaction and density-induced velocity reduction. This is achieved by applying kernel estimates of pedestrian density to describe the pedestrian mass in the perceived surroundings of an agent. The applicability of the model is investigated by means of numerical simulations using three speed distribution scenarios and three arrival rate scenarios. The simulation results are in correspondence with expectations and recommendations related to capacity for day-use facilities in national parks (pedestrian level of service D). The model mimics the expected trail capacity behaviour represented by arrival rate, leading to speed deterioration and stoppages. Heterogeneity of the agents similarly as non-homogeneity of arrival rate leads to clogging at smaller average arrival rates.
Mapping Technological Futures: Anticipatory Discourse Through Text Mining
Autoři
Skórski, M.; Landowska, A.; Rajda, K.
Rok
2025
Publikováno
Humanities & Social Sciences Communications. 2025, 1(1), 1-20. ISSN 2662-9992.
Multitask learning for cognitive sciences triplet analysis
Autoři
Stambrouski, T.; da Silva Alves, R.
Rok
2025
Publikováno
Expert Systems with Applications. 2025, 267 1-10. ISSN 0957-4174.
Typ
Článek
Anotace
The triplet-based odd-one-out problem, which involves trials where human subjects are asked to select the most different concept among three, is a well-studied task in cognitive sciences. With the release of a large triplet-based dataset, THINGS, there has been a recent surge in the popularity of machine learning models aimed at learning mathematical representations of object concepts, such as SPoSE, VICE, and CARE. The first two models learn representations by maximizing the similarity between the two most similar objects, while the latter diverges by directly learning the odd-one-out, making its embedding more distant. No prior attempts have integrated both paradigms, which are important for understanding object representation in cognitive science. In this paper, we propose MASTER, a multitask learning method for the triplet problem that encapsulates both paradigms. Our results demonstrate that our method not only better predicts the odd-one-out object but also provides insightful representations for studying these concepts. Furthermore, we studied the conditions under which each model performs better, offering valuable insights for future research on how these paradigms affect human understanding of object concepts.
Odd chromatic number of graph classes
Autoři
Belmonte, R.; Harutyunyan, A.; Kohler, N.; Melissinos, N.
Rok
2025
Publikováno
Journal of Graph Theory. 2025, 108(4), 722-744. ISSN 0364-9024.
Typ
Článek
Anotace
A graph is called odd (respectively, even) if every vertex has odd (respectively, even) degree. Gallai proved that every graph can be partitioned into two even induced subgraphs, or into an odd and an even induced subgraph. We refer to a partition into odd subgraphs as an odd colouring of G $G$. Scott proved that a connected graph admits an odd colouring if and only if it has an even number of vertices. We say that a graph G $G$ is k $k$-odd colourable if it can be partitioned into at most k $k$ odd induced subgraphs. The odd chromatic number of G $G$, denoted by chi odd( G ) ${\chi }_{\text{odd}}(G)$, is the minimum integer k $k$ for which G $G$ is k $k$-odd colourable. We initiate the systematic study of odd colouring and odd chromatic number of graph classes. We first consider a question due to Scott, which states that every graph G $G$ of even order n $n$ has chi odd( G ) <= c n ${\chi }_{\text{odd}}(G)\le c\sqrt{n}$, for some positive constant c $c$, by proving that this is indeed the case if G $G$ is restricted to having girth at least seven. We also show that any graph G $G$ whose all components have even order satisfies chi odd( G ) <= 2 Delta - 1 ${\chi }_{\text{odd}}(G)\le 2{\rm{\Delta }}-1$, where Delta ${\rm{\Delta }}$ is the maximum degree of G $G$. Next, we show that certain interesting classes have bounded odd chromatic number. Our main results in this direction are that interval graphs, graphs of bounded modular-width all have bounded odd chromatic number. In particular, every even interval graph is 6-odd colourable, and every even graph is 3 m w $3mw$-odd colourable, where m w $mw$ is the modular width of a graph.
On certain equivalences of metric spaces
Autoři
Rok
2025
Publikováno
Proceedings of the American Mathematical Society. 2025, 153(1), 239-249. ISSN 0002-9939.
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Článek
Anotace
The normed spaces of molecules constructed by Arens and Eells allow us to define two natural equivalence relations on the class of complete metric spaces. We say that two complete metric spaces M and N are M at- equivalent if their normed spaces of molecules are isomorphic and we say that they are .F- equivalent if the corresponding completions - the Lipschitz-free Banach spaces .F ( M ) and .F ( N ) - are isomorphic. In this note, we compare these and some other relevant equivalences of metric spaces. Clearly, M at-equivalent spaces are .F-equivalent. Our main result states that M at-equivalent spaces must have the same covering dimension. In combination with the work of Godard, this implies that M at-equivalence is indeed strictly stronger than .F-equivalence. However, M at-equivalent spaces need not be homeomorphic, as we demonstrate through a general construction. We also observe that M at-equivalence does not preserve the Assouad dimension. We introduce a natural notion of a free basis to simplify the notation.