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Wyniki wyszukiwania dla: graph algorithms

Wyniki wyszukiwania dla: graph algorithms

  • On minimum cost edge searching

    Publikacja

    We consider the problem of finding edge search strategies of minimum cost. The cost of a search strategy is the sum of searchers used in the clearing steps of the search. One of the natural questions is whether it is possible to find a search strategy that minimizes both the cost and the number of searchers used to clear a given graph G. We call such a strategy ideal. We prove, by an example, that ideal search strategies do not...

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  • Bounds on the cover time of parallel rotor walks

    Publikacja

    - JOURNAL OF COMPUTER AND SYSTEM SCIENCES - Rok 2016

    The rotor-router mechanism was introduced as a deterministic alternative to the random walk in undirected graphs. In this model, a set of k identical walkers is deployed in parallel, starting from a chosen subset of nodes, and moving around the graph in synchronous steps. During the process, each node successively propagates walkers visiting it along its outgoing arcs in round-robin fashion, according to a fixed ordering. We consider...

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  • Necessary and Sufficient Condition for State-Independent Contextual Measurement Scenarios

    Publikacja

    - PHYSICAL REVIEW LETTERS - Rok 2014

    The problem of identifying measurement scenarios capable of revealing state-independent contextuality in a given Hilbert space dimension is considered. We begin by showing that for any given dimension d and any measurement scenario consisting of projective measurements, (i) the measure of contextuality of a quantum state is entirely determined by its spectrum, so that pure and maximally mixed states represent the two extremes...

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  • Coronas and Domination Subdivision Number of a Graph

    In this paper, for a graph G and a family of partitions P of vertex neighborhoods of G, we define the general corona G ◦P of G. Among several properties of this new operation, we focus on application general coronas to a new kind of characterization of trees with the domination subdivision number equal to 3.

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  • Wordventure - cooperative wordnet editor. Architecture for lexical semantic aquisition

    Publikacja

    - Rok 2009

    This article presents architecture for acquiring lexical semanticsin a collaborative approach paradigm. The system enablesfunctionality for editing semantic networks in a wikipedia-like style. The core of the system is a user-friendly interface based on interactive graph navigation.It has been used for semantic network presentation,and brings simultaneously modification functionality.

  • Joanna Raczek dr inż.

    Wykształcenie 1997 -- 2001 Studia inżynierskie, Wydział Fizyki Technicznej i Matematyki Stosowanej, Politechnika Gdańska. Kierunek: Matematyka, specjalność: Matematyka Stosowana. 2001 -- 2003 Studia magisterskie, Wydział Fizyki Technicznej i Matematyki Stosowanej, Politechnika Gdańska. Kierunek: Matematyka, specjalność: Matematyka Stosowana. 2000 -- 2004 Studia inżynierskie, Wydział Elektroniki, Informatyki i Telekomunikacji,...

  • WordVenture - COOPERATIVE WordNet EDITOR Architecture for Lexical Semantic Acquisition

    Publikacja

    - Rok 2017

    This article presents architecture for acquiring lexical semantics in a collaborative approach paradigm. The system enables functionality for editing semantic networks in a wikipedia-like style. The core of the system is a user-friendly interface based on interactive graph navigation. It has been used for semantic network presentation, and brings simultaneously modification functionality.

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  • Distributed NVRAM Cache – Optimization and Evaluation with Power of Adjacency Matrix

    Publikacja

    In this paper we build on our previously proposed MPI I/O NVRAM distributed cache for high performance computing. In each cluster node it incorporates NVRAMs which are used as an intermediate cache layer between an application and a file for fast read/write operations supported through wrappers of MPI I/O functions. In this paper we propose optimizations of the solution including handling of write requests with a synchronous mode,...

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  • Turán numbers for odd wheels

    Publikacja

    - DISCRETE MATHEMATICS - Rok 2018

    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...

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  • Zero-Visibility Cops and Robber Game on a Graph

    Publikacja

    - LECTURE NOTES IN COMPUTER SCIENCE - Rok 2013

    We examine the zero-visibility cops and robber graph searching model, which differs from the classical cops & robber game in one way: the robber is invisible. We show that this model is not monotonic. We also provide bounds on both the zero-visibility copnumber and monotonic zero-visibility copnumber in terms of the pathwidth.

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  • A Systematic Search for New Coupling Schemes of Cross-Coupled Resonator Bandpass Filters

    Publikacja

    In this paper, a systematic approach to an extensive search for topologies of cross-coupled filters with generalized Chebyshev response is presented. The technique applies graph theory to find unique, nonisomorphic filter configurations, and tests whether a specific frequency response can be realized in a given set of topologies. The results of the search are then stored in a database of possible filter configurations.

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  • Block graphs with large paired domination multisubdivision number

    Publikacja

    The paired domination multisubdivision number of a nonempty graph G, denoted by msdpr(G), is the smallest positive integer k such that there exists an edge which must be subdivided k times to increase the paired domination number of G. It is known that msdpr(G) ≤ 4 for all graphs G. We characterize block graphs with msdpr(G) = 4.

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  • Parity vertex colouring of graphs

    Publikacja

    - Discussiones Mathematicae Graph Theory - Rok 2011

    A parity path in a vertex colouring of a graph is a path along which each colour is used an even number of times. Let Xp(G) be the least number of colours in a proper vertex colouring of G having no parity path. It is proved that for any graph G we have the following tight bounds X(G) <= Xp(G) <=|V(G)|− a(G)+1, where X(G) and a(G) are the chromatic number and the independence number of G, respectively. The bounds are improved for...

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  • New potential functions for greedy independence and coloring

    Publikacja

    - DISCRETE APPLIED MATHEMATICS - Rok 2015

    A potential function $f_G$ of a finite, simple and undirected graph $G=(V,E)$ is an arbitrary function $f_G : V(G) \rightarrow \mathbb{N}_0$ that assigns a nonnegative integer to every vertex of a graph $G$. In this paper we define the iterative process of computing the step potential function $q_G$ such that $q_G(v)\leq d_G(v)$ for all $v\in V(G)$. We use this function in the development of new Caro-Wei-type and Brooks-type...

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  • Optimal edge-coloring with edge rate constraints

    Publikacja

    - NETWORKS - Rok 2013

    We consider the problem of covering the edges of a graph by a sequence of matchings subject to the constraint that each edge e appears in at least a given fraction r(e) of the matchings. Although it can be determined in polynomial time whether such a sequence of matchings exists or not [Grötschel et al., Combinatorica (1981), 169–197], we show that several questions about the length of the sequence are computationally intractable....

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  • A note on mixed tree coloring

    Publikacja

    - INFORMATION PROCESSING LETTERS - Rok 2008

    Zaproponowano liniowy algorytm dla problemu kolorowania mieszanego w drzewach, uzyskując tym samym poprawę w stosunku do algorytmu o złożoności O(n^2) podanego w pracy [P. Hansen, J. Kuplinsky, D. de Werra, Mixed graph colorings, Math. Methods Oper. Res. 45 (1997) 145-160].

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  • An approximation algorithm for maximum P3-packing in subcubic graphs

    Publikacja

    W pracy podano algorytm 4/3-przyliżony dla trudnego obliczeniowo problemu umieszczania wierzchołkowo rozłącznych dwukrawędziowych ścieżek w grafach o stopniu maksymalnym 3 i stopniu minimalnym 2. Poprawiono tym samym wcześniejsze wyniki dla grafów kubicznych (A. Kelmans, D. Mubayi, Journal of Graph Theory 45, 2004).

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  • Network Approach to Increments of RR-intervals for Visualization of Dynamics of Cardiac Regulation

    Publikacja

    - Rok 2014

    The transition network for RR -increments is pre- sented in a directed and weighted graph, with vertices represent- ing RR -increments and edges corresponding to the order in a sequence of increments. The adjacency matrix and the transition matrix of this network provide a graphical tool which could be useful in the assessment of cardiac regulation. As an example, the method is applied in detecting differences between diurnal activity...

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  • An Approximation of the Zero Error Capacity by a Greedy Algorithm

    Publikacja

    - Rok 2020

    We present a greedy algorithm that determines a lower bound on the zero error capacity. The algorithm has many new advantages, e.g., it does not store a whole product graph in a computer memory and it uses the so-called distributions in all dimensions to get a better approximation of the zero error capacity. We also show an additional application of our algorithm.

  • An Approximation of the Zero Error Capacity by a Greedy Algorithm.

    Publikacja

    - Rok 2020

    We present a greedy algorithm that determines a lower bound on the zero error capacity. The algorithm has many new advantages, e.g., it does not store a whole product graph in a computer memory and it uses the so-called distributions in all dimensions to get a better approximation of the zero error capacity. We also show an additional application of our algorithm.

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  • Recognition, understanding and aestheticization of freehand drawing flowcharts

    Publikacja

    - Rok 2007

    In this paper a concept of FCA, a system for recognizing, understanding and aestheticization of freehand drawing flow charts is described. The system is based on a proposed by the author FlowGram graph grammar describing flow charts drawing. An open format FlowChartML for flow charts description is also proposed. The aestheticization criterion is formulated that allows for automatic beautification of flow charts. First experiments...

  • Separability Assessment of Selected Types of Vehicle-Associated Noise

    Music Information Retrieval (MIR) area as well as development of speech and environmental information recognition techniques brought various tools in-tended for recognizing low-level features of acoustic signals based on a set of calculated parameters. In this study, the MIRtoolbox MATLAB tool, designed for music parameter extraction, is used to obtain a vector of parameters to check whether they are suitable for separation of...

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  • The convex domination subdivision number of a graph

    Publikacja

    Let G = (V;E) be a simple graph. A set D\subset V is a dominating set of G if every vertex in V - D has at least one neighbor in D. The distance d_G(u, v) between two vertices u and v is the length of a shortest (u, v)-path in G. An (u, v)-path of length d_G(u; v) is called an (u, v)-geodesic. A set X\subset V is convex in G if vertices from all (a, b)-geodesics belong to X for any two vertices a, b \in X. A set X is a convex dominating...

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  • Parallel immune system for graph coloring

    Publikacja

    - Rok 2008

    This paper presents a parallel artificial immune system designed forgraph coloring. The algorithm is based on the clonal selection principle. Each processor operates on its own pool of antibodies and amigration mechanism is used to allow processors to exchange information. Experimental results show that migration improves the performance of the algorithm. The experiments were performed using a high performance cluster on a set...

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  • Complexity Issues on of Secondary Domination Number

    Publikacja

    - ALGORITHMICA - Rok 2023

    In this paper we study the computational complexity issues of the problem of secondary domination (known also as (1, 2)-domination) in several graph classes. We also study the computational complexity of the problem of determining whether the domination and secondary domination numbers are equal. In particular, we study the influence of triangles and vertices of degree 1 on these numbers. Also, an optimal algorithm for finding...

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  • Application of Doubly Connected Dominating Sets to Safe Rectangular Smart Grids

    Publikacja

    - ENERGIES - Rok 2022

    Smart grids, together with the Internet of Things, are considered to be the future of the electric energy world. This is possible through a two-way communication between nodes of the grids and computer processing. It is necessary that the communication is easy and safe, and the distance between a point of demand and supply is short, to reduce the electricity loss. All these requirements should be met at the lowest possible cost....

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  • Switched-capacitor DC-DC converters in arbitrary switching mode - topologically derived resistive models based on incremental graph approach.

    In the preceding paper we reviewed some of modeling approaches aimed at systematic formulation and solution of switched capacitor DC-DC converters. In our review, special attention was paid to computationally efficient and mathematically elegant methods. In so doing we had tried to demonstrate the virtues of unified Incremental Graph (IG) approach. Incremental Graph is, in concept, a tool originally created for analysis and synthesis...

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  • The complexity of minimum-length path decompositions

    Publikacja

    We consider a bi-criteria generalization of the pathwidth problem, where, for given integers k, l and a graph G, we ask whether there exists a path decomposition P of G such that the width of P is at most k and the number of bags in P, i.e., the length of P, is at most l. We provide a complete complexity classification of the problem in terms of k and l for general graphs. Contrary to the original pathwidth problem, which is fixed-parameter...

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  • 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...

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  • Cooperative Word Net Editor for Lexical Semantic Acquisition

    Publikacja

    - Rok 2011

    The article describes an approach for building Word Net semantic dictionary in a collaborative approach paradigm. The presented system system enables functionality for gathering lexical data in a Wikipedia-like style. The core of the system is a user-friendly interface based on component for interactive graph navigation. The component has been used for Word Net semantic network presentation on web page, and it brings functionalities...

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  • Generalized Gradient Equivariant Multivalued Maps, Approximation and Degree

    Publikacja

    Consider the Euclidean space Rn with the orthogonal action of a compact Lie group G. We prove that a locally Lipschitz G-invariant mapping f from Rn to R can be uniformly approximated by G-invariant smooth mappings g in such a way that the gradient of g is a graph approximation of Clarke’s generalized gradient of f . This result enables a proper development of equivariant gradient degree theory for a class of set-valued gradient...

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  • 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...

  • T-colorings, divisibility and circular chromatic number

    Let T be a T-set, i.e., a finite set of nonnegative integers satisfying 0 ∈ T, and G be a graph. In the paper we study relations between the T-edge spans espT (G) and espd⊙T (G), where d is a positive integer and d ⊙ T = {0 ≤ t ≤ d (max T + 1): d |t ⇒ t/d ∈ T} . We show that espd⊙T (G) = d espT (G) − r, where r, 0 ≤ r ≤ d − 1, is an integer that depends on T and G. Next we focus on the case T = {0} and show that espd⊙{0} (G) =...

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  • Proposal of a method for effective tasks distribution in the execution of compolex problems

    An access to a great number of various services allows for decomposition of complex problems into smaller and less complex tasks. Those tasks can be presented in a form of a dependency graph. This paper shows an idea of executing such a problem using cooperating autonomous agents. Main focus of this work is cooperation covering effective tasks distribution among executors. This paper presents an algorithm for dynamic executor selection...

  • Reliability of production machines in the bakery industry – theoretical and practical issues

    Publikacja

    The aim of the article is to present probabilistic models, which were then used to analyze the reliability of production machines in the baking industry. The author conducted research in the period from January 2, 2016 to December 31, 2018 regarding the measurement of reliability of a traditional production system based on a probabilistic concept. Due to the limited scope of the article, reliability calculations for a set of thermo-oil...

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  • Port-Based Modelling of Distributed-Lumped Parameter Systems

    Publikacja

    There in the paper is presented an uniform, port-based approach to modelling of both lumped and distributed parameter systems. Port-based model of the distributed system has been defined by application of bond graph methodology and distributed transfer function method (DTFM). The approach proposed combines versatility of port-based modelling and accuracy of distributed transfer function method. The concise representation of lumped-distributed...

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  • ProSIL Software for functional saferty management in life cycle = Aplikacja ProSIL do zarządzania bezpieczeństwem funkcjonalnym w cyklu życia

    In the paper the ProSIL software to aid the functional safety management is presented. The software consists of three modules to aid: determination of the required SIL level (ProSILen), veryfication of the SIL level (ProSILver). In the aplication the method of the calibrated risk graph to determine the required safety integrity level SIL for defined safety instrumented functions is applied. The methods concerning functional safety...

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  • Optimal backbone coloring of split graphs with matching backbones

    For a graph G with a given subgraph H, the backbone coloring is defined as the mapping c: V(G) -> N+ such that |c(u)-c(v)| >= 2 for each edge uv \in E(H) and |c(u)-c(v)| >= 1 for each edge uv \in E(G). The backbone chromatic number BBC(G;H) is the smallest integer k such that there exists a backbone coloring with max c(V(G)) = k. In this paper, we present the algorithm for the backbone coloring of split graphs with matching backbone.

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  • Polyhedral Ramsey Numbers

    Given two polygons or polyhedrons P1 and P2, we can transform these figures to graphs G1 and G2, respectively. The polyhedral Ramsey number Rp(G1,G2) is the smallest integer n such that every graph, which represents polyhedron on n vertices either contains a copy of G1 or its complement contains a copy of G2. Using a computer search together with some theoretical results we have established some polyhedral Ramsey numbers, for example...

  • Study of the Flow Dynamics of Surface Water Masses in the Area of the Coastal Gulf of Gdansk

    Publikacja

    - Rok 2017

    The paper describes two methods of predicting the movement of small objects with surface water masses. One of the methods uses graph theory to describe the motion of water masses in port docks. The results of this study were compared to a simulation using the hydrodynamic numerical model M3D. The results obtained in a virtual environment were related to the experiments in the real world. In the coastal area of the Gulf of Gdansk,...

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  • Chromatic cost coloring of weighted bipartite graphs

    Given a graph G and a sequence of color costs C, the Cost Coloring optimization problem consists in finding a coloring of G with the smallest total cost with respect to C. We present an analysis of this problem with respect to weighted bipartite graphs. We specify for which finite sequences of color costs the problem is NP-hard and we present an exact polynomial algorithm for the other finite sequences. These results are then extended...

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  • Graph Representation Integrating Signals for Emotion Recognition and Analysis

    Data reusability is an important feature of current research, just in every field of science. Modern research in Affective Computing, often rely on datasets containing experiments-originated data such as biosignals, video clips, or images. Moreover, conducting experiments with a vast number of participants to build datasets for Affective Computing research is time-consuming and expensive. Therefore, it is extremely important to...

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  • Theoretical modelling of efficient fire safety water networks by certified domination

    Publikacja

    - Scientific Reports - Rok 2024

    This paper explores a new way of designing water supply networks for fire safety using ideas from graph theory, focusing on a method called certified domination. Ensuring a good water supply is crucial for fire safety in communities, this study looks at the rules and problems in Poland for how much water is needed to fight fires in different areas and how this can be achieved at a lowest possible cost. We present a way to plan...

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  • A construction for the hat problem on a directed graph

    Publikacja

    A team of n players plays the following game. After a strategy session, each player is randomly fitted with a blue or red hat. Then, without further communication, everybody can try to guess simultaneously his own hat color by looking at the hat colors of the other players. Visibility is defined by a directed graph; that is, vertices correspond to players, and a player can see each player to whom he is connected by an arc. The...

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  • 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. We require that the strategy is connected and monotone, that is, at each point of the execution the part of the graph...

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  • Certified domination

    Publikacja

    Imagine that we are given a set D of officials and a set W of civils. For each civil x ∈ W, there must be an official v ∈ D that can serve x, and whenever any such v is serving x, there must also be another civil w ∈ W that observes v, that is, w may act as a kind of witness, to avoid any abuse from v. What is the minimum number of officials to guarantee such a service, assuming a given social network? In this paper, we introduce...

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  • A city is not a tree: a multi-city study on street network and urban life

    Publikacja

    Christopher Alexander, a British-American scholar, differentiated an old (natural) city from a new (planned) one by structure. The former resembles a “semilattice”, or a complex system encompassing many interconnected sub-systems. The latter is shaped in a graph-theoretical “tree”, which lacks the structural complexity as its sub-systems are compartmentalized into a single hierarchy. This structural distinction explains why, or...

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  • On trees with equal domination and total outer-independent domination numbers

    Publikacja

    For a graph G=(V,E), a subset D subseteq V(G) is a dominating set if every vertex of V(G)D has a neighbor in D, while it is a total outer-independent dominating set if every vertex of G has a neighbor in D, and the set V(G)D is independent. The domination (total outer-independent domination, respectively) number of G is the minimum cardinality of a dominating (total outer-independent dominating, respectively) set of G. We characterize...

  • On trees with equal 2-domination and 2-outer-independent domination numbers

    For a graph G = (V,E), a subset D \subseteq V(G) is a 2-dominating set if every vertex of V(G)\D$ has at least two neighbors in D, while it is a 2-outer-independent dominating set if additionally the set V(G)\D is independent. The 2-domination (2-outer-independent domination, respectively) number of G, is the minimum cardinality of a 2-dominating (2-outer-independent dominating, respectively) set of G. We characterize all trees...

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  • Comparison of hydrogen bonds and diverse weak interactions of the nitro group in 2-methyl-4-nitroanilinium nitrate, bisulfate and two hexafluoridosilicates: elementary graph-set approach

    Crystal structures of (H2m4na)NO3 (1), (H2m4na)HSO4 (2), (H2m4na)2SiF6 (3) and (H2m4na)2SiF6*2H2O (4), where 2m4na = 2-methyl-4-nitroaniline, are presented. Two layers of interactions occur in the structures, N—H...O/F hydrogen bonds and interactions with the nitro group. Although diverse, hydrogen-bonding patterns are compared with each other by means of interrelations among elementary graph-set descriptors and descriptors of hydrogen-bonding...

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