# Katedra Algorytmów i Modelowania Systemów

## Publikacje

• wyników na stronę:
• rok:
tytuł:

wszystkich: 396

## Katalog

• ### 2018

• #### Turán numbers for odd wheels

The Turán number ex(n,G) is the maximum number of edges in any n-vertex graph that does not contain a subgraph isomorphic to G. A wheel W_n is a graph on n vertices obtained from a C_{n−1} by adding one vertex w and making w adjacent to all vertices of the C_{n−1}. We obtain two exact values for small wheels: ex(n,W_5)=\lfloor n^2/4+n/2\rfloor, ex(n,W_7)=\lfloor n^2/4+n/2+1 \rfloor. Given that ex(n,W_6) is already known, this...
• Pełny tekst w serwisie zewnętrznym
• #### Trade-offs in multiparty Bell-inequality violations in qubit networks

R. Ramanathan, P. Mironowicz - PHYSICAL REVIEW A - 2018
Two overlapping bipartite binary input Bell inequalities cannot be simultaneously violated as this would contradict the usual no-signalling principle. This property is known as monogamy of Bell inequality violations and generally Bell monogamy relations refer to trade-offs between simultaneous violations of multiple inequalities. It turns out that multipartite Bell inequalities admit weaker forms of monogamies that allow for violations...
• Pełny tekst w serwisie zewnętrznym
• #### Tight bounds on the complexity of semi-equitable coloring of cubic and subcubic graphs

H. Furmańczyk, M. Kubale - DISCRETE APPLIED MATHEMATICS - 2018
We consider the complexity of semi-equitable k-coloring, k>3, of the vertices of a cubic or subcubic graph G. In particular, we show that, given a n-vertex subcubic graph G, it is NP-complete to obtain a semi-equitable k-coloring of G whose non-equitable color class is of size s if s>n/3, and it is polynomially solvable if s, n/3.
• #### System information propagation for composite structures

We study in details decoherence process of a spin register, coupled to a spin environment. We use recently developed methods of information transfer study in open quantum systems to analyze information flow between the register and its environment. We show that there are regimes when not only the register decoheres effectively to a classical bit string, but this bit string is redundantly encoded in the environment, making it available...
• Pełny tekst w serwisie zewnętrznym
• #### Steering is an essential feature of non-locality in quantum theory

R. Ramanathan, D. Goyeneche, S. Muhammad, P. Mironowicz, M. Grünfeld, M. Bourennane, P. Horodecki - Nature Communications - 2018
A physical theory is called non-local when observers can produce instantaneous effects over distant systems. Non-local theories rely on two fundamental effects: local uncertainty relations and steering of physical states at a distance. In quantum mechanics, the former one dominates the other in a well-known class of non-local games known as XOR games. In particular, optimal quantum strategies for XOR games are completely determined...
• Pełny tekst w serwisie zewnętrznym
• #### Shared processor scheduling

We study the shared processor scheduling problem with a single shared processor to maximize total weighted overlap, where an overlap for a job is the amount of time it is processed on its private and shared processor in parallel. A polynomial-time optimization algorithm has been given for the problem with equal weights in the literature. This paper extends that result by showing an (log)-time optimization algorithm for a class...
• Pełny tekst w serwisie zewnętrznym
• #### Scheduling of unit-length jobs with cubic incompatibility graphs on three uniform machines

H. Furmańczyk, M. Kubale - DISCRETE APPLIED MATHEMATICS - 2018
We consider the problem of scheduling n identical jobs on 3 uniform machines with speeds s1, s2, and s3 to minimize the schedule length. We assume that jobs are subject to some kind of mutual exclusion constraints, modeled by a cubic incompatibility graph. We how that if the graph is 2-chromatic then the problem can be solved in O(n^2) time. If the graph is 3-chromatic, the problem becomes NP-hard even if s1>s2=s3.
• Pełny tekst w serwisie zewnętrznym
• #### Oxygen sensitivity of hydrogenesis’ and methanogenesis’

In the chapter, results of dark fermentation of sour cabbage in presence of oxygen with concentrations 2-9% are presented. The presence of oxygen in such concentration inhibits methanogesis (and methane production more than 2 times) and increases hydrogen production 6 times. It also shortens the fermentation process above 40%.
• Pełny tekst w serwisie zewnętrznym
• #### On-line Search in Two-Dimensional Environment

We consider the following on-line pursuit-evasion problem. A team of mobile agents called searchers starts at an arbitrary node of an unknown network. Their goal is to execute a search strategy that guarantees capturing a fast and invisible intruder regardless of its movements using as few searchers as possible. As a way of modeling two-dimensional shapes, we restrict our attention to networks that are embedded into partial grids:...
• Pełny tekst w serwisie zewnętrznym
• #### On incidence coloring of coloring of complete multipartite and semicubic bipartite graphs

In the paper, we show that the incidence chromatic number of a complete k-partite graph is at most ∆+2 (i.e., proving the incidence coloring conjecture for these graphs) and it is equal to ∆+1 if and only if the smallest part has only one vertex.
• Pełny tekst w serwisie zewnętrznym
• #### Non-monotone graph searching models

Graph searching encompasses a variety of different models, many of which share a property that in optimal strategies fugitive can never access once searched regions. Monotonicity, as it is called, is vital in many established results in the field however its absence significantly impedes the analysis of a given problem. This survey attempts to gather non-monotone models, that are less researched in effort of summarizing the results...
• #### Metody oceny jakości łączy bezprzewodowych wykorzystywanych w systemie netBaltic

Przedstawiono metodę oceny jakości łączy, opracowaną w ramach projektu netBaltic, która powstała w wyniku analizy danych zgromadzonych podczas wielu kampanii pomiarowych na wodach Morza Bałtyckiego oraz badań i testów prowadzonych w środowisku laboratoryjnym. Przedstawiono definicję parametru LQI (Link Quality Indicator) oraz sposób jego wyznaczania dla sieci komórkowych 3G i LTE oraz dla łączy bezprzewodowych WiFi. Zaprezentowano...
• Pełny tekst w serwisie zewnętrznym

Pokazano, że pewien problem transportu produktów chemicznych może być sprowadzony do problemu szeregowania identycznych zadań kompatybilnych na wsadowych maszynach jednorodnych i rozwiązany metodami kolorowania grafów. Ponieważ problem ten jest NP-trudny, zbadano przypadki szczególne, które dają się rozwiązać w czasie kwadratowym. Rozważania ogólne są wsparte doświadczeniami komputerowymi zebranymi w trakcie implementacji wybranych...
• #### Dynamic F-free Coloring of Graphs

P. Borowiecki, E. Sidorowicz - GRAPHS AND COMBINATORICS - 2018
A problem of graph F-free coloring consists in partitioning the vertex set of a graph such that none of the resulting sets induces a graph containing a fixed graph F as an induced subgraph. In this paper we consider dynamic F-free coloring in which, similarly as in online coloring, the graph to be colored is not known in advance; it is gradually revealed to the coloring algorithm that has to color each vertex upon request as well...
• Pełny tekst w serwisie zewnętrznym
• #### Connections between Mutually Unbiased Bases and Quantum Random Access Codes

E. Aguilar Lozano, J. Borkała, P. Mironowicz, M. Pawłowski, - PHYSICAL REVIEW LETTERS - 2018
We present a new quantum communication complexity protocol, the promise--Quantum Random Access Code, which allows us to introduce a new measure of unbiasedness for bases of Hilbert spaces. The proposed measure possesses a clear operational meaning and can be used to investigate whether a specific number of mutually unbiased bases exist in a given dimension by employing Semi--Definite Programming techniques.
• Pełny tekst w serwisie zewnętrznym
• #### Computational aspects of greedy partitioning of graphs

In this paper we consider a variant of graph partitioning consisting in partitioning the vertex set of a graph into the minimum number of sets such that each of them induces a graph in hereditary class of graphs P (the problem is also known as P-coloring). We focus on the computational complexity of several problems related to greedy partitioning. In particular, we show that given a graph G and an integer k deciding if the greedy...
• Pełny tekst w serwisie zewnętrznym
• #### Collaborative Exploration of Trees by Energy-Constrained Mobile Robots

S. Das, D. Dereniowski, C. Karousatou - THEORY OF COMPUTING SYSTEMS - 2018
We study the problem of exploration of a tree by mobile agents (robots) that have limited energy. The energy constraint bounds the number of edges that can be traversed by a single agent. We use a team of agents to collectively explore the tree and the objective is to minimize the size of this team. The agents start at a single node, the designated root of the tree and the height of the tree is assumed to be less than the energy...
• Pełny tekst w serwisie zewnętrznym
• #### Brief Announcement: Energy Constrained Depth First Search

D. Shantanu, D. Dereniowski, P. Uznański - 2018
Depth first search is a natural algorithmic technique for constructing a closed route that visits all vertices of a graph. The length of such route equals, in an edge-weighted tree, twice the total weight of all edges of the tree and this is asymptotically optimal over all exploration strategies. This paper considers a variant of such search strategies where the length of each route is bounded by a positive integer B (e.g. due...
• Pełny tekst w serwisie zewnętrznym
• #### ANALIZA MOŻLIWOŚCI WYKORZYSTANIA TRANSFORMACJI FALKOWEJ DO DETEKCJI NIEZAJĘTYCH PASM CZĘSTOTLIWOŚCI

K. Bronk, D. Rutkowski, B. Wereszko, K. Wereszko, K. Żurek - Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne - 2018
Celem pracy była implementacja oraz wykonanie badań efektywności wybranej metody wykrywania niezajętych zasobów częstotliwości, opartej na wyznaczaniu entropii sygnału z wykorzystaniem analizy falkowej. W referacie przedstawiono podstawy teoretyczne rozważanych zagadnień, wyniki przeprowadzonych badań laboratoryjnych i ich analizę oraz wnioski.
• Pełny tekst w serwisie zewnętrznym
• ### 2017

• #### The Snow Team Problem

D. Dereniowski, A. Lingas, M. Persson, D. Osula, P. Żyliński - 2017
We study several problems of clearing subgraphs by mobile agents in digraphs. The agents can move only along directed walks of a digraph and, depending on the variant, their initial positions may be pre-specified. In general, for a given subset~$\cS$ of vertices of a digraph $D$ and a positive integer $k$, the objective is to determine whether there is a subgraph $H=(\cV_H,\cA_H)$ of $D$ such that (a) $\cS \subseteq \cV_H$, (b)...
• Pełny tekst w serwisie zewnętrznym
• #### Szybkość przeszukiwania grafu

R. Ostrowski - 2017
Przeszukiwanie grafu pojawiło się jako problem matematyczny ponad 40 lat temu i w najogólniejszej wersji zajmuje się odszukiwaniem jednostki-uciekiniera niezależnie od jego poczynań. Od tamtej pory uzyskano wiele wyników odpowiadających na pytanie o minimalną ilość poszukujących jednostek w różnorodnych modelach, czyli odpowiednią liczbę przeszukiwawczą (ang. serach number) grafu. Popularne warianty problemów przeszukiwania obejmują...
• #### Szeregowanie zadań dwuprocesorowych w systemach otwartych

W pracy rozważany jest problem szeregowania zadań dwuoperacyjnych w systemie otwartym (open-shop), z kryterium minimalizacji długości harmonogramu oraz sumy czasów zakończenia wszystkich zadań. Zakładając jednostkowe czasy wykonywania operacji można stosować efektywne metody chromatyczne rozwiązywania problemu, poprzez sprowadzenie go do modelu grafowego oraz zastosowanie w nim wybranego modelu kolorowania, które pozwala uzyskać...
• Pełny tekst w serwisie zewnętrznym
• #### Shared multi-processor scheduling

We study shared multi-processor scheduling problem where each job can be executed on its private processor and simultaneously on one of many processors shared by all jobs in order to reduce the job’s completion time due to processing time overlap. The total weighted overlap of all jobs is to be maximized. The problem models subcontracting scheduling in supply chains and divisible load scheduling in computing. We show that synchronized...
• Pełny tekst w serwisie zewnętrznym
• #### Scheduling of unit-length jobs with bipartite incompatibility graphs on four uniform machines

The problem of scheduling n identical jobs on 4 uniform machines with speeds s1>=s2>=s3>=s4 is considered.The aim is to find a schedule with minimum possible length. We assume that jobs are subject to mutual exclusion constraints modeled by a bipartite incompatibility graph of degree delta. We show that the general problem is NP-hard even if s1=s2=s3. If, however, delta<5 and s1>12s2 s2=s3=s4, then the problem can be solved to...
• Pełny tekst w serwisie zewnętrznym
• #### Scheduling of identical jobs with bipartite incompatibility graphs on uniform machines. Computational experiments

We consider the problem of scheduling unit-length jobs on three or four uniform parallel machines to minimize the schedule length or total completion time. We assume that the jobs are subject to some types of mutual exclusion constraints, modeled by a bipartite graph of a bounded degree. The edges of the graph correspond to the pairs of jobs that cannot be processed on the same machine. Although the problem is generally NP-hard,...
• Pełny tekst w serwisie zewnętrznym
• #### Równowaga strategiczna dla zbiorów defensywnych w drzewach

W pracy rozważany jest problem defensywnej równowagi strategicznej dla zbiorów defensywnych w drzewach (spójnych grafach acyklicznych), który polega na znalezieniu dwóch rozłącznych globalnych zbiorów defensywnych. Zagadnienie to znajduje zastosowanie w modelo- waniu problemów komunikacyjnych w sieciach. Dla danego grafu G podzbiór jego wierzchołków S jest zbiorem defensywnym, jeśli dla każdego wierzchołka v należącego do S spełniony...
• Pełny tekst w serwisie zewnętrznym
• #### Restricted open shop scheduling

In the real applications the open shop scheduling models often require some additional constraints and adequate models. We concern the restrictions in the open shop scheduling related to an instance of the problem and to a feasible solution. Precisely, we require that each jobs consists of the bounded number of operations and each machine has a bounded load (i.e., the total number of operations executed on this machine in a schedule)....
• Pełny tekst w serwisie zewnętrznym
• #### Realizacja zadań w grafie przez grupę mobilnych jednostek

D. Osula - 2017
Grupa mobilnych jednostek, nazywanych także agentami, jest umiejscowiona w jednym lub wielu wierzchołkach grafu nazywanych bazami. Stamtąd poruszając się po z góry znanym (offline) lub nieznanym (online) grafie muszą wykonać powierzone im zadanie, takie jak przeszukanie grafu, spotkanie, dekontaminacja grafu czy wybór lidera. Celem jest znalezienie optymalnej, rozproszonej, deterministycznej strategii (sekwencji ruchów jednostek),...
• Pełny tekst w portalu
• #### On Computational Aspects of Greedy Partitioning of Graphs

P. Borowiecki - 2017
In this paper we consider a problem of graph P-coloring consisting in partitioning the vertex set of a graph such that each of the resulting sets induces a graph in a given additive, hereditary class of graphs P. We focus on partitions generated by the greedy algorithm. In particular, we show that given a graph G and an integer k deciding if the greedy algorithm outputs a P-coloring with a least k colors is NP-complete for an infinite...
• Pełny tekst w serwisie zewnętrznym
• #### No-Wait & No-Idle Open Shop Minimum Makespan Scheduling with Bioperational Jobs

In the open shop scheduling with bioperational jobs each job consists of two unit operations with a delay between the end of the first operation and the beginning of the second one. No-wait requirement enforces that the delay between operations is equal to 0. No-idle means that there is no idle time on any machine. We model this problem by the interval incidentor (1, 1)-coloring (IIR(1, 1)-coloring) of a graph with the minimum...
• Pełny tekst w portalu
• #### Monitoring of the Process of System Information Broadcasting in Time

One of the problems of quantum physics is how a measurement turns quantum, noncopyable data, towards copyable classical knowledge. We use the quantum state discrimination in a central system model to show how its evolution leads to the broadcasting of the information, and how orthogonalization and decoherence factors allow us to monitor the distance of the state in question to the one perfectly broadcasting information, in any...
• Pełny tekst w serwisie zewnętrznym
• #### Interval incidence coloring of subcubic graphs

In this paper we study the problem of interval incidence coloring of subcubic graphs. In [14] the authors proved that the interval incidence 4-coloring problem is polynomially solvable and the interval incidence 5-coloring problem is N P-complete, and they asked if χii(G) ≤ 2∆(G) holds for an arbitrary graph G. In this paper, we prove that an interval incidence 6-coloring always exists for any subcubic graph G with ∆(G) = 3.
• Pełny tekst w serwisie zewnętrznym
• #### Gdańska Międzynarodowa Szkoła Letnia na WETI

M. Kubale - Pismo PG - 2017
W dniach 5-12 września 2017 roku Katedra Algorytmów i Modelowania Systemów23, przy wydatnej pomocy,WETI, zorganizowała Międzynarodową Szkołę Letnią poświęconą algorytmom dla problemów optymalizacji dyskretnej.
• #### Equitable coloring of corona multiproducts of graphs

H. Furmańczyk, M. Kubale, V. Mkrtchyan - Discussiones Mathematicae Graph Theory - 2017
We give some results regarding the equitable chromatic number for l-corona product of two graphs: G and H, where G is an equitably 3- or 4-colorable graph and H is an r-partite graph, a cycle or a complete graph. Our proofs lead to polynomial algorithms for equitable coloring of such graph products provided that there is given an equitable coloring of G.
• #### Complementarity between entanglement-assisted and quantum distributed random access code

A. Hameedi, D. Saha, P. Mironowicz, M. Pawłowski, M. Bourennane - PHYSICAL REVIEW A - 2017
Collaborative communication tasks such as random access codes (RACs) employing quantum resources have manifested great potential in enhancing information processing capabilities beyond the classical limitations. The two quantum variants of RACs, namely, quantum random access code (QRAC) and the entanglement-assisted random access code (EARAC), have demonstrated equal prowess for a number of tasks. However, there do exist specific...
• Pełny tekst w serwisie zewnętrznym
• #### Comparing Phylogenetic Trees by Matching Nodes Using the Transfer Distance Between Partitions

D. Bogdanowicz, K. Giaro - JOURNAL OF COMPUTATIONAL BIOLOGY - 2017
Ability to quantify dissimilarity of different phylogenetic trees describing the relationship between the same group of taxa is required in various types of phylogenetic studies. For example, such metrics are used to assess the quality of phylogeny construction methods, to define optimization criteria in supertree building algorithms, or to find horizontal gene transfer (HGT) events. Among the set of metrics described so far in...
• Pełny tekst w serwisie zewnętrznym
• #### Collision-free network exploration

J. Czyzowicz, D. Dereniowski, L. Gąsieniec, R. Klasing, A. Kosowski, D. Pająk - JOURNAL OF COMPUTER AND SYSTEM SCIENCES - 2017
Mobile agents start at different nodes of an n-node network. The agents synchronously move along the network edges in a collision-free way, i.e., in no round two agents may occupy the same node. An agent has no knowledge of the number and initial positions of other agents. We are looking for the shortest time required to reach a configuration in which each agent has visited all nodes and returned to its starting location. In...
• Pełny tekst w serwisie zewnętrznym
• #### Collaborative Delivery by Energy-Sharing Low-Power Mobile Robots

E. Bampas, S. Das, D. Dereniowski, C. Karousatou - 2017
We study two variants of delivery problems for mobile robots sharing energy. Each mobile robot can store at any given moment at most two units of energy, and whenever two robots are at the same location, they can transfer energy between each other, respecting the maximum capacity. The robots operate in a simple graph and initially each robot has two units of energy. A single edge traversal by an robot reduces its energy by one...
• Pełny tekst w serwisie zewnętrznym
• #### Average distance is submultiplicative and subadditive with respect to the strong product of graphs

We show that the average distance is submultiplicative and subadditive on the set of non-trivial connected graphs with respect to the strong product. We also give an application of the above-mentioned result.
• Pełny tekst w serwisie zewnętrznym
• #### Approximation Strategies for Generalized Binary Search in Weighted Trees

D. Dereniowski, A. Kosowski, P. Uznański, M. Zou - 2017
We consider the following generalization of the binary search problem. A search strategy is required to locate an unknown target node t in a given tree T. Upon querying a node v of the tree, the strategy receives as a reply an indication of the connected component of T\{v} containing the target t. The cost of querying each node is given by a known non-negative weight function, and the considered objective is to minimize the total...
• Pełny tekst w serwisie zewnętrznym
• ### 2016

• #### Topology recognition and leader election in colored networks

Topology recognition and leader election are fundamental tasks in distributed computing in networks. The first of them requires each node to find a labeled isomorphic copy of the network, while the result of the second one consists in a single node adopting the label 1 (leader), with all other nodes adopting the label 0 and learning a path to the leader. We consider both these problems in networks whose nodes are equipped with...
• Pełny tekst w serwisie zewnętrznym
• #### Szeregowanie identycznych zadań na czterech procesorach jednorodnych z dwudzielnymi grafami konfliktów

M. Kubale - 2016
Rozważono problem szeregowania n zadań jednostkowych na 4 procesorach jednorodnych o szybkościach s1>=s2>=s3>=s4. Celem szeregowania jest utworzenie najkrótszego możliwego harmonogramu. Zadania podlegają ograniczeniom zasobowym mówiącym, że niektóre pary zadań nie mogą być wykonane na tym samym procesorze. Podajemy algorytm dokładny, który rozwiązuje problem w czasie liniowym, o ile graf niezgodności jest kubiczny. Ponadto podajemy...
• #### Strategic balance in graphs

For a given graph G, a nonempty subset S contained in V ( G ) is an alliance iff for each vertex v ∈ S there are at least as many vertices from the closed neighbourhood of v in S as in V ( G ) − S. An alliance is global if it is also a dominating set of G. The alliance partition number of G was defined in Hedetniemi et al. (2004) to be the maximum number of sets in a partition of V ( G ) such that each set is an alliance. Similarly,...
• Pełny tekst w serwisie zewnętrznym
• #### Sharp bounds for the complexity of semi-equitable coloring of cubic and subcubic graphs

M. Kubale, H. Furmańczyk - 2016
In this paper we consider the complexity of semi-equitable k-coloring of the vertices of a cubic or subcubic graph. We show that, given n-vertex subcubic graph G, a semi-equitable k-coloring of G is NP-hard if s >= 7n/20 and polynomially solvable if s <= 7n/21, where s is the size of maximum color class of the coloring.
• Pełny tekst w serwisie zewnętrznym
• #### On the hardness of computing span of subcubic graphs

In the paper we study the problem of finding ξ-colorings with minimal span, i.e. the difference between the largest and the smallest color used.
• Pełny tekst w serwisie zewnętrznym
• #### On some open questions for Ramsey and Folkman numbers

S. Radziszowski, X. Xiaodong - 2016
We discuss some of our favorite open questions about Ramsey numbers and a related problem on edge Folkman numbers. For the classical two-color Ramsey numbers, we first focus on constructive bounds for the difference between consecutive Ramsey numbers. We present the history of progress on the Ramsey number R(5,5) and discuss the conjecture that it is equal to 43.
• #### On bipartization of cubic graphs by removal of an independent set

H. Furmańczyk, M. Kubale, S. Radziszowski - DISCRETE APPLIED MATHEMATICS - 2016
We study a new problem for cubic graphs: bipartization of a cubic graph Q by deleting sufficiently large independent set.
• Pełny tekst w serwisie zewnętrznym
• #### Normal-form preemption sequences for an open problem in scheduling theory

B. Chen, E. Coffman, D. Dereniowski, W. Kubiak - JOURNAL OF SCHEDULING - 2016
Structural properties of optimal preemptive schedules have been studied in a number of recent papers with a primary focus on two structural parameters: the minimum number of preemptions necessary, and a tight lower bound on shifts, i.e., the sizes of intervals bounded by the times created by preemptions, job starts, or completions. These two parameters have been investigated for a large class of preemptive scheduling problems,...
• Pełny tekst w serwisie zewnętrznym
• #### Non-isolating bondage in graphs

A dominating set of a graph $G = (V,E)$ is a set $D$ of vertices of $G$ such that every vertex of $V(G) \setminus D$ has a neighbor in $D$. The domination number of a graph $G$, denoted by $\gamma(G)$, is the minimum cardinality of a dominating set of $G$. The non-isolating bondage number of $G$, denoted by $b'(G)$, is the minimum cardinality among all sets of edges $E' \subseteq E$ such that $\delta(G-E') \ge 1$ and \$\gamma(G-E')...
• Pełny tekst w serwisie zewnętrznym
• #### Network Graph Transformation Providing Fast Calculation of Paths for Resilient Routing

Protection of transmission against failures can be appropriately dealt with by alternative paths. However, common schemes (e.g., Bhandaris scheme) are characterized by a remarkable delay while determining the transmission paths. This in turn may have a serious impact on serving dynamic demands (characterized by relatively short duration time). As a remedy to this problem, we introduce an approach to pre-compute the sets of disjoint...