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2. More results on the domination number of Cartesian product of two directed cyclesAnsheng Ye, Fang Miao, Zehui Shao, Jia-Bao Liu, Janez Žerovnik, Polona Repolusk, 2019, original scientific article Abstract: Let γ(D) denote the domination number of a digraph D and let C$_m$□C$_n$ denote the Cartesian product of C$_m$ and C$_n$, the directed cycles of length n ≥ m ≥ 3. Liu et al. obtained the exact values of γ(C$_m$□C$_n$) for m up to 6 [Domination number of Cartesian products of directed cycles, Inform. Process. Lett. 111 (2010) 36–39]. Shao et al. determined the exact values of γ(C$_m$□C$_n$) for m = 6, 7 [On the domination number of Cartesian product of two directed cycles, Journal of Applied Mathematics, Volume 2013, Article ID 619695]. Mollard obtained the exact values of γ(C$_m$□C$_n$) for m = 3k + 2 [M. Mollard, On domination of Cartesian product of directed cycles: Results for certain equivalence classes of lengths, Discuss. Math. Graph Theory 33(2) (2013) 387–394.]. In this paper, we extend the current known results on C$_m$□C$_n$ with m up to 21. Moreover, the exact values of γ(C$_n$□C$_n$) with n up to 31 are determined.
Keywords: domination number, Cartesian product, directed cycle
Published in DKUM: 02.09.2022; Views: 611; Downloads: 13
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3. Roman domination number of the Cartesian products of paths and cyclesPolona Repolusk, Janez Žerovnik, 2012, original scientific article Abstract: Roman domination is a historically inspired variety of general domination such that every vertex is labeled with labels from $\{0,1,2\}$. Roman domination number is the smallest of the sums of labels fulfilling condition that every vertex, labeled 0, has a neighbor, labeled 2. Using algebraic approach we give ▫$O(C)$▫ time algorithm for computing Roman domination number of special classes of polygraphs (rota- and fasciagraphs). By implementing the algorithm we give formulas for Roman domination number of the Cartesian products of paths and cycles ▫$P_n \Box P_k$▫, ▫$P_n \Box C_k$▫ for ▫$k \leq 8$▫ and ▫$n \in {\mathbb N}$▫ and for ▫$C_n \Box P_k$▫ and ▫$C_n \Box C_k$▫ for ▫$k \leq 5$▫, ▫$n \in {\mathbb N}$▫. We also give a list of Roman graphs among investigated families.
Keywords: graph theory, Roman domination number, Cartesian product, polygraphs, path algebra
Published in DKUM: 23.08.2017; Views: 1634; Downloads: 267
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4. Razred grafov H(n, k)Nuša Flajšman, 2016, undergraduate thesis Abstract: Naj bosta n in k naravni števili in n≥k. To diplomsko delo predstavlja nov razred grafov H(n,k), ki vsebuje hiperkocke ter Johnsonove in Kneserjeve grafe kot njegove podgrafe.
V prvem poglavju so povzeti osnovni pojmi iz teorije grafov, v drugem delu pa bodo predstavljeni nekateri rezultati vezani na družino H(n,k).
Na primer, H(n,k) ima maksimalno povezanost (n nad k), H(n,k) je Hamiltonov, če je k liho število ter je sestavljen iz dveh izomorfnih povezanih komponent, če je k sodo število.
Keywords: teorija grafov, hiperkocke, hamiltonovi grafi, Johnsonovi grafi, Kneserjevi grafi
Published in DKUM: 23.09.2016; Views: 1946; Downloads: 110
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5. O mavričnem dominantnem številuAnastazija Tacer, 2016, undergraduate thesis Abstract: V diplomskem delu ugotavljamo meje t-mavričnega dominantnega števila za poljuben graf.
Kadar je t = 3, govorimo o 3-mavrični dominantni funkciji. Pri označevanju vozlišč se omejimo na cikle (Cn), poti (Pn) in posplošene Petersenove grafe P(n,k). Zapišemo meje 3-mavričnega dominantnega števila za poti in cikle in nekatere posplošene Petersenove grafe.
Keywords: Mavrično dominantno število, mavrična dominantna funkcija, cikel, pot, posplošen Petersenov graf.
Published in DKUM: 10.03.2016; Views: 2009; Downloads: 117
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6. A note on the domination number of the Cartesian products of paths and cyclesPolona Repolusk, Janez Žerovnik, 2011 Abstract: Z uporabo algebraičnega pristopa implementiramo konstantni algoritem za računanje dominantnega števila kartezičnih produktov poti in ciklov. Podamo formule za dominantna števila ▫$gamma(P_n Box C_k)$▫ (za ▫$k leq 11$▫, ▫$n in {mathbb N}$)▫ in dominantna števila ▫$gamma(C_n Box P_k)$▫ in ▫$gamma(C_n Box C_k)$▫ (za ▫$k leq 6$▫, ▫$n in {mathbb N}$▫).
Keywords: teorija grafov, kartezični produkt, grid, torus, dominacija, algebra poti, konstantni algoritem, graph theory, Cartesian product, grid graph, torus, graph domination, path algebra, constant time algorithm
Published in DKUM: 10.07.2015; Views: 1740; Downloads: 41
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7. Roman domination number of the Cartesian products of paths and cyclesPolona Repolusk, Janez Žerovnik, 2011, original scientific article Abstract: Rimska dominacija je zgodovinsko utemeljena različica običajne dominacije, pri kateri vozlišča grafa označimo z oznakami iz množice ▫${0,1,2}$▫ tako, da ima vsako vozlišče z oznako 0 soseda z oznako 2. Najmanjšo izmed vsot oznak grafa imenujemo rimsko dominantno število grafa. Z uporabo algebraičnega pristopa dobimo konstantni algoritem za računanje rimskega dominantnega števila posebne vrste poligrafov: rota- in fasciagrafov. V posebnih primerih izračunamo formule za rimsko dominanto število kartezičnega produkta poti in ciklov ▫$P_n Box P_k$▫, ▫$P_n Box C_k$▫ za ▫$k leq 8$▫ in ▫$n in {mathbb N}$▫ ter za ▫$C_n Box P_k$▫ in ▫$C_n Box C_k$▫ za ▫$k leq 5$▫, ▫$n in {mathbb N}$▫. Dodan je seznam rimskih grafov med kartezičnimi produkti zgoraj omenjenih poti in ciklov.
Keywords: teorija grafov, kartezični produkt, rimsko dominantno število, poligrafi, algebra poti, graph theory, Roman domination number, Cartesian product, polygraphs, path algebra
Published in DKUM: 10.07.2015; Views: 1762; Downloads: 75
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8. On the Roman domination in the lexicographic product of graphsTadeja Kraner Šumenjak, Polona Repolusk, Aleksandra Tepeh, 2012, original scientific article Abstract: A Roman dominating function of a graph ▫$G = (V,E)$▫ is a function ▫$f colon V to {0,1,2}$▫ such that every vertex with ▫$f(v) = 0$▫ is adjacent to some vertex with ▫$f(v) = 2$▫. The Roman domination number of ▫$G$▫ is the minimum of ▫$w(f) = sum_{v in V}f(v)$▫ over all such functions. Using a new concept of the so-called dominating couple we establish the Roman domination number of the lexicographic product of graphs. We also characterize Roman graphs among the lexicographic product of graphs.
Keywords: teorija grafov, rimska dominacija, popolna dominacija, leksikografski produkt, graph theory, Roman domination, total domination, lexicographic product
Published in DKUM: 10.07.2015; Views: 1844; Downloads: 110
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