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Wyświetlanie 1-15 z 71
Tytuł:
Proof Compression and NP Versus PSPACE II: Addendum
Autorzy:
Gordeev, Lew
Haeusler, Edward Hermann
Powiązania:
https://bibliotekanauki.pl/articles/2142754.pdf
Data publikacji:
2022-01-07
Wydawca:
Uniwersytet Łódzki. Wydawnictwo Uniwersytetu Łódzkiego
Tematy:
graph theory
natural deduction
computational complexity
Opis:
In our previous work we proved the conjecture NP = PSPACE by advanced proof theoretic methods that combined Hudelmaier’s cut-free sequent calculus for minimal logic (HSC) with the horizontal compressing in the corresponding minimal Prawitz-style natural deduction (ND). In this Addendum we show how to prove a weaker result NP = coNP without referring to HSC. The underlying idea (due to the second author) is to omit full minimal logic and compress only “naive” normal tree-like ND refutations of the existence of Hamiltonian cycles in given non-Hamiltonian graphs, since the Hamiltonian graph problem in NPcomplete. Thus, loosely speaking, the proof of NP = coNP can be obtained by HSC-elimination from our proof of NP = PSPACE.
Źródło:
Bulletin of the Section of Logic; 2022, 51, 2; 197-205
0138-0680
2449-836X
Pojawia się w:
Bulletin of the Section of Logic
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Tendencies of Chinese subways’ spatial growth in 2000-2020
Tendencje rozwoju przestrzennego chińskiego metra w latach 2000-2020
Autorzy:
Panov, Roman
Powiązania:
https://bibliotekanauki.pl/articles/34656099.pdf
Data publikacji:
2022
Wydawca:
Uniwersytet Gdański. Komisja Geografii Komunikacji Polskiego Towarzystwa Geograficznego
Tematy:
subway network
spatial structure
China
graph theory
sieć metra
struktura przestrzenna
Chiny
teoria grafów
Opis:
One of the main transportation problems of biggest modern cities is the excessively high load on ground transport, which is why the development of subway networks is of particular importance. This article analyzes the development of the spatial structure of subway networks in China. Currently China shows an intensive growth of existing networks and massive openings of new networks, which makes it the most suitable object for studying the evolution of subway networks. The methodology developed by K. Kansky and S. A. Tarkhov was used as the theoretical basis of this study. The study was conducted by analyzing the dynamics of the main quantitative and topomorphological indicators of subway networks during their passage through the stages of spatial evolution. The following indicators were used: the number of subways, the total length of the network, the number of cycles in the network, the number of topological layers and the number of cycles in each of them, the number of branching tiers, the area of topological layers and their share in the cyclic core of the network, the distribution of the length between the elements of the network structure, average cycle size, topological limit, cyclization index and circuity index. We identified the patterns for passing the stages of evolutionary development by the networks of Chinese subways; also, we found common features that define the “Chinese” type of subway, we identified a new subtype of networks.
Źródło:
Prace Komisji Geografii Komunikacji PTG; 2022, 25(2); 42-51
1426-5915
2543-859X
Pojawia się w:
Prace Komisji Geografii Komunikacji PTG
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A note on possible density and diameter of countere xamples to the Seymour’s second neighborhood conjecture
Autorzy:
Zelenskiy, Oleksiy
Darmosiuk, Valentyna
Nalivayko, Illia
Powiązania:
https://bibliotekanauki.pl/articles/2052069.pdf
Data publikacji:
2021
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
graph theory
Seymour’s second neighborhood conjecture
density of graph
diameter of graph
Opis:
Seymour’s second neighborhood conjecture states that every simple digraph without loops or 2-cycles contains a vertex whose second neighborhood is at least as large as its first. In this paper we show, that from falsity of Seymour’s second neighborhood conjecture it follows that there exist strongly-connected counterexamples with both low and high density (dense and sparse graph). Moreover, we show that if there is a counterexample to conjecture, then it is possible to construct counterexample with any diameter k ≥ 3
Źródło:
Opuscula Mathematica; 2021, 41, 4; 601-605
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An ant algorithm for the maximum number of 3-cliques in 3-partite graphs
Autorzy:
Schiff, Krzysztof
Powiązania:
https://bibliotekanauki.pl/articles/2183443.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
ant colony optimization
three-partite graph
3-clique
combinatorial optimization
graph theory
Opis:
The problem of finding the maximum number of d- vertices cliques (d = 3) in d-partite graph (d = 3) when graph density q is lower than 1 is an important problem in combinatorial optimization and it is one of many NP-complete problems. For this problem a meta-heuristic algorithm has been developed, namely an ant colony optimization algorithm. In this paper a new development of this ant algorithm and experimental results are presented. The problem of finding the maximum number of 3-vertices cliques can be encountered in computer image analysis, computer vision applications, automation and robotic vision systems. The optimal solution of this problem boils down to finding a set of 3-vertices cliques in a 3-partite graph and this set should have cardinality as high as possible. The elaborated ant colony algorithm can be easily modified for d-dimensional problems, that is for finding the maximum number of d-vertices cliques in a d-partite graph.
Źródło:
Control and Cybernetics; 2021, 50, 2; 347--358
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An application of persistent homology and the graph theory to linguistics: The case of Tifinagh and Phoenician scripts
Autorzy:
Bouazzaoui, Hajar
Elomary, Mohamed Abdou
Mamouni, My Ismail
Powiązania:
https://bibliotekanauki.pl/articles/1827549.pdf
Data publikacji:
2021-09-06
Wydawca:
Główny Urząd Statystyczny
Tematy:
topological data analysis
persistent homology
graph theory
writing systems
Abjad scripts
Alphabet scripts
Tifinagh script
Phoenician script
Opis:
As the origin of the Tifinagh script remains uncertain, this work aims at exploring its probable relatedness with the Phoenician script. Using tools from within topological data analysis and graph theory, the similarity between the two scripts is studied. The clustering of their letter shapes is performed based on the pairwise distances between their topological signatures. The ideas presented in this work can be extended to study the similarity between any two writing systems and as such can serve as the first step for linguists to determine the possibly related scripts before conducting further analysis.
Źródło:
Statistics in Transition new series; 2021, 22, 3; 141-156
1234-7655
Pojawia się w:
Statistics in Transition new series
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Multi-sourced power system restoration strategy based on modified Prim’s algorithm
Autorzy:
Łukaszewski, Artur
Nogal, Łukasz
Powiązania:
https://bibliotekanauki.pl/articles/2086893.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
self-healing grid
micro-grid
reconfiguration
greedy algorithms
graph theory
simulations
Prim’s algorithm
siatka samoleczenia
mikrosiatka
rekonfiguracja
algorytmy zachłanne
teoria grafów
symulacje
algorytm Prima
Opis:
Self-healing grids are one of the most developing concepts applied in electrical engineering. Each restoration strategy requires advanced algorithms responsible for the creation of local power systems. Multi-agent automation solutions dedicated for smart grids are mostly based on Prim’s algorithm. Graph theory in that field also leaves many problems unsolved. This paper is focused on a variation of Prim’s algorithm utility for a multi-sourced power system topology. The logic described in the paper is a novel concept combined with a proposal of a multi-parametrized weight calculation formula representing transmission features of energy delivered to loads present in a considered grid. The weight is expressed as the combination of three elements: real power, reactive power, and real power losses. The proposal of a novel algorithm was verified in a simulation model of a power system. The new restoration logic was compared with the proposal of the strategy presented in other recently published articles. The novel concept of restoration strategy dedicated to multi-sourced power systems was verified positively by simulations. The proposed solution proved its usefulness and applicability.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2021, 69, 5; e137942, 1--12
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Użyteczność badawcza struktur sieciowych w nauce o stosunkach międzynarodowych
Usability of network structures in the research of international relations
Autorzy:
Stachyra, Wojciech
Powiązania:
https://bibliotekanauki.pl/articles/1857650.pdf
Data publikacji:
2021-03-31
Wydawca:
Wydawnictwo Adam Marszałek
Tematy:
stosunki międzynarodowe
metodologia
system międzynarodowy
sieci
teoria grafów
international relations
methodology
international system
networks
graph theory
Opis:
Artykuł zawiera argumentację na rzecz wykorzystania w nauce o stosunkach międzynarodowych metod badawczych opartych na analizie struktur sieciowych. Wychodząc od ogólnej definicji sieci jako struktury złożonej z połączonych relacjami elementów, ukazuje jej odpowiedniość do opisu procesów i zjawisk o charakterze transgranicznym. Idąc dalej, rozważa komplementarność sieci w stosunku do kategorii badawczej systemu międzynarodowego i metody analizy systemowej, która przedstawia się jako szczególny przypadek szerszej klasy sieciowych metod badawczych. Analiza dotychczasowych, udanych prób adaptacji w naukach społecznych matematycznej teorii grafów, pozwala na zaproponowanie ogólnego modelu analizy sieciowej, który może okazać się użyteczny przy badaniu stosunków międzynarodowych.
The presented article contains argumentation supporting the use of network structure analysis as a method of research in International Relations. By applying the general definition of the network as a structure built with a set of interconnected elements, it can be shown that such a method is suitable for description of transborder processes and phenomena. Under this reasoning, the article explores the complementarity of the network approach in relation to the international system research category and the method of systemic analysis. The latter appears to be a specific case of the broader class of network methods. The comparison of previous, successful attempts at application of the mathematical graph theory in social research allows for making a proposal of a general model of network analysis in International Relations.
Źródło:
Athenaeum. Polskie Studia Politologiczne; 2021, 70; 159-174
1505-2192
Pojawia się w:
Athenaeum. Polskie Studia Politologiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Compared Costs of Domination Location-Domination and Identification
Autorzy:
Hudry, Olivier
Lobstein, Antoine
Powiązania:
https://bibliotekanauki.pl/articles/32083840.pdf
Data publikacji:
2020-02-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
graph theory
dominating set
locating-dominating code
identifying code
twin-free graph
Opis:
Let G = (V, E) be a finite graph and r ≥ 1 be an integer. For v ∈ V, let Br(v) = {x ∈ V : d(v, x) ≤ r} be the ball of radius r centered at v. A set C ⊆ V is an r-dominating code if for all v ∈ V, we have Br(v) ∩ C ≠ ∅; it is an r-locating-dominating code if for all v ∈ V, we have Br(v) ∩ C ≠ ∅, and for any two distinct non-codewords x ∈ V \ C, y ∈ V \ C, we have Br(x) ∩ C ≠ Br(y) ∩ C; it is an r-identifying code if for all v ∈ V, we have Br(v) ∩ C ≠ ∅, and for any two distinct vertices x ∈ V, y ∈ V, we have Br(x) ∩ C ≠ Br(y) ∩ C. We denote by γr(G) (respectively, ldr(G) and idr(G)) the smallest possible cardinality of an r-dominating code (respectively, an r-locating-dominating code and an r-identifying code). We study how small and how large the three differences idr(G)−ldr(G), idr(G)−γr(G) and ldr(G) − γr(G) can be.
Źródło:
Discussiones Mathematicae Graph Theory; 2020, 40, 1; 127-147
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The reactive power and voltage control management strategy based on virtual reactance cloud control
Autorzy:
Zhang, Wei Min
Zhang, Yan Xia
Powiązania:
https://bibliotekanauki.pl/articles/949903.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
cloud model
graph theory
virtual reactance
voltage reactive power management
Opis:
The paper aims at the higher reactive power management complexity caused by the access of distributed power, and the problem such as large data exchange capacity, low accuracy of reactive power distribution, a slow convergence rate, and so on, may appear when the controlled objects are large. This paper proposes a reactive power and voltage control management strategy based on virtual reactance cloud control. The coupling between active power and reactive power in the system is effectively eliminated through the virtual reactance. At the same time, huge amounts of data are treated to parallel processing by using the cloud computing model parallel distributed processing, realize the uncertainty transformation between qualitative concept and quantitative value. The power distribution matrix is formed according to graph theory, and the accurate allocation of reactive power is realized by applying the cloud control model. Finally, the validity and rationality of this method are verified by testing a practical node system through simulation.
Źródło:
Archives of Electrical Engineering; 2020, 69, 4; 921-936
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Reducing pollution levels generated by short sea shipping : use of Bayesian networks to analyse the utilization of liquefied natural gas as an alternative fuel
Autorzy:
Molina Serrano, Beatriz
González Cancelas, Nicoleta
Soler Flores, Francisco
Powiązania:
https://bibliotekanauki.pl/articles/246442.pdf
Data publikacji:
2019
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
Bayesian networks
graph theory
artificial network
European Union
Short Sea Shipping
liquefied natural gas
Opis:
Pollution adjacent to the continent's shores has increased in the last decades, so it has been necessary to establish an energy policy to improve environmental conditions. One of the proposed solution was the search of alternative fuels to the commonly used in Short Sea Shipping to reduce pollution levels in Europe. Studies and researches show that liquefied natural gas could meet the European Union environmental requirements. Even environmental benefits are important; currently there is not significant number of vessels using it as fuel. Moreover, main target of this article is exposing result of a research in which a methodology to establish the most relevant variables in the decision to implement liquefied natural gas in Short Sea Shipping has been development using data mining. A Bayesian network was constructed because this kind of network allows to get graphically the relationships between variables and to determine posteriori values that quantify their contributions to decision-making. Bayesian model has been done using data from some European countries (European Union, Norway and Iceland) and database was generated by 35 variables classified in 5 categories. Main obtained conclusion in this analysis is that variables of transport and international trade and economy and finance are the most relevant in the decision-making process when implementing liquefied natural gas. Even more, it can be stablish that capacity of liquefied natural gas regasification terminals under construction and modal distribution of water cargo transportation continental as the most decisive variables because they are the root nodes in the obtained network.
Źródło:
Journal of KONES; 2019, 26, 1; 147-158
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Vehicle Recognition New Approach with the Application of Graph Network Theory
Autorzy:
Agarwal, Richa
Powiązania:
https://bibliotekanauki.pl/articles/1159223.pdf
Data publikacji:
2018
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Component
Graph Theory
Neural Network
Vehicle Recognition
Opis:
A vehicle recognition approach based on graph theory and neural networks is proposed in this paper. In this approach, image threshold method described in this paper based on spectral theory is used for image pre-processing. And after filter of undetermined regions with rules, regions left are unified. These values are input into neural network to recognize vehicle and vehicle types. The experiment proves that this method has high recognition rate and low false rate.
Źródło:
World Scientific News; 2018, 113; 37-43
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of selected transportation network structures based on graph measures
Autorzy:
Żochowska, R.
Soczówka, P.
Powiązania:
https://bibliotekanauki.pl/articles/197600.pdf
Data publikacji:
2018
Wydawca:
Politechnika Śląska. Wydawnictwo Politechniki Śląskiej
Tematy:
transportation network
graph theory
graph measures
topological measure
sieć transportowa
teoria grafów
wykres miar
miara topologiczna
Opis:
The structure of transportation networks has been the subject of analysis for many years, due to the important role that it plays in assessing the efficiency of transportation systems. One of the most common approaches to representing this structure is to use graph theory, in which elements of transportation infrastructure are depicted by a set of vertices and edges. An approach based on graph theory allows us to assess the structure of a transportation network in terms of connectivity, accessibility, density or complexity. In the paper, different transportation network structures are assessed and compared, based on graph measures.
Źródło:
Zeszyty Naukowe. Transport / Politechnika Śląska; 2018, 98; 223-233
0209-3324
2450-1549
Pojawia się w:
Zeszyty Naukowe. Transport / Politechnika Śląska
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Clustering based on eigenvectors of the adjacency matrix
Autorzy:
Lucińska, M.
Wierzchoń, S. T.
Powiązania:
https://bibliotekanauki.pl/articles/331178.pdf
Data publikacji:
2018
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
spectral clustering
adjacency matrix eigenvalues
adjacency matrix eigenvectors
graph perturbation theory
eigengap heuristics
klastrowanie widmowe
macierz sąsiedztwa
teoria grafów
Opis:
The paper presents a novel spectral algorithm EVSA (eigenvector structure analysis), which uses eigenvalues and eigenvectors of the adjacency matrix in order to discover clusters. Based on matrix perturbation theory and properties of graph spectra we show that the adjacency matrix can be more suitable for partitioning than other Laplacian matrices. The main problem concerning the use of the adjacency matrix is the selection of the appropriate eigenvectors. We thus propose an approach based on analysis of the adjacency matrix spectrum and eigenvector pairwise correlations. Formulated rules and heuristics allow choosing the right eigenvectors representing clusters, i.e., automatically establishing the number of groups. The algorithm requires only one parameter—the number of nearest neighbors. Unlike many other spectral methods, our solution does not need an additional clustering algorithm for final partitioning. We evaluate the proposed approach using real-world datasets of different sizes. Its performance is competitive to other both standard and new solutions, which require the number of clusters to be given as an input parameter.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2018, 28, 4; 771-786
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On some aspects of graph theory for optimal transport among marine ports
Autorzy:
Chládek, P.
Smetanová, D.
Krile, S.
Powiązania:
https://bibliotekanauki.pl/articles/196424.pdf
Data publikacji:
2018
Wydawca:
Politechnika Śląska. Wydawnictwo Politechniki Śląskiej
Tematy:
graph theory
minimum spanning tree
seaport
Travelling Salesman Problem
teoria grafów
minimalne drzewo spinające
port morski
Opis:
This paper is devoted to the Travelling Salesman Problem as applied to Czechoslovak ocean shipping companies and their marine ports on the Black Sea. The shortest circular path around these ports is found and discussed. Formulation of the problem accounts for the fact that distances between the individual cities are not the same in both directions. The consequences that arise from this situation are studied. The used algorithms are based on graph theory and standard logistic methods. In addition, the results are compared with the results obtained by using a minimum spanning tree algorithm.
Źródło:
Zeszyty Naukowe. Transport / Politechnika Śląska; 2018, 101; 37-45
0209-3324
2450-1549
Pojawia się w:
Zeszyty Naukowe. Transport / Politechnika Śląska
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the topological properties of the certain neural networks
Autorzy:
Liu, J.-B.
Zhao, J.
Wang, S.
Javaid, M.
Cao, J.
Powiązania:
https://bibliotekanauki.pl/articles/91804.pdf
Data publikacji:
2018
Wydawca:
Społeczna Akademia Nauk w Łodzi. Polskie Towarzystwo Sieci Neuronowych
Tematy:
neural network
topological indices
graph theory
Opis:
A topological index is a numeric quantity associated with a network or a graph that characterizes its whole structural properties. In [Javaid and Cao, Neural Computing and Applications, DOI 10.1007/s00521-017-2972-1], the various degree-based topological indices for the probabilistic neural networks are studied. We extend this study by considering the calculations of the other topological indices, and derive the analytical closed formulas for these new topological indices of the probabilistic neural network. Moreover, a comparative study using computer-based graphs has been carried out first time to clarify the nature of the computed topological descriptors for the probabilistic neural networks. Our results extend some known conclusions.
Źródło:
Journal of Artificial Intelligence and Soft Computing Research; 2018, 8, 4; 257-268
2083-2567
2449-6499
Pojawia się w:
Journal of Artificial Intelligence and Soft Computing Research
Dostawca treści:
Biblioteka Nauki
Artykuł
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