1. Wide diameter of Cartesian graph bundlesIztok Banič, Janez Žerovnik, 2010, objavljeni znanstveni prispevek na konferenci Opis: Fault tolerance and transmission delay of networks are important concepts in network design. The notions are strongly related to connectivity and diameter of a graph, and have been studied by many authors. Wide diameter of a graph combines studying connectivity with the diameter of a graph. Diameter with width ▫$k$▫ of a graph ▫$G$▫, ▫$k$▫-diameter, is defined as the minimum integer ▫$d$▫ for which there exist at least ▫$k$▫ internally disjoint paths of length at most ▫$d$▫ between any two distinct vertices in ▫$G$▫. Denote by ▫${mathscr D}_c(G)$▫ the ▫$c$▫-diameter of ▫$G$▫ and ▫$kappa(G)$▫ the connectivity of ▫$G$▫. In the context of computer networks, wide diameters of Cartesian graph products have been recently studied by many authors. Cartesian graph bundles is a class of graphs that is a generalization of the Cartesian graph products. Let ▫$G$▫ be a Cartesian graph bundle with fiber ▫$F$▫ over base ▫$B$▫, ▫$0 < a le kappa(F)$▫, and ▫$0 < b le kappa(B)$▫. We prove that ▫${mathscr D}_{a+b}(G) le {mathscr D}_a(F) + {mathscr D}_b(B) + 1$▫. Moreover, if ▫$G$▫ is a graph bundle with fiber ▫$F ne K_2$▫ over base ▫$B ne K_2$▫, then ▫${mathscr D}_{a+b}(G) le {mathscr D}_a(F) + {mathscr D}_b(B)$▫. The bounds are tight.
Ključne besede: mathematics, graph theory, Cartesian graph products, Cartesian graph bundles, wide diameter
Objavljeno: 07.06.2012; Ogledov: 1255; Prenosov: 69
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2. Fault-diameter of Cartesian product of graphs and Cartesian graph bundlesIztok Banič, Janez Žerovnik, 2006 Opis: Cartesian graph bundles is a class of graphs that is a generalization of the Cartesian graph products. Let ▫$G$▫ be a ▫$k_G$▫-connected graph and ▫${mathcal{D}}_c(G)$▫ denote the diameter of ▫$G$▫ after deleting any of its ▫$c < k_G$▫ vertices. We prove that if ▫$G_1, G_2, dots, G_q$▫ are ▫$k_1$▫-connected, ▫$k_2$▫-connected,...,▫$k_q$▫-connected graphs and ▫$0 leq a_1 < k_1$▫, ▫$0 leq a_2 < k_2$▫,...,▫$0 leq a_q < k_q$▫ and ▫$a = a_1 + a_2 + dots + a_q + (q-1)$▫, then the fault diameter of ▫$G$▫, a Cartesian product of ▫$G_1$▫, ▫$G_2$▫,...,▫$G_q$▫, with ▫$a$▫ faulty nodes is ▫${mathcal{D}}_{a}(G) leq {mathcal{D}}_{a_1}(G_1)+{mathcal{D}}_{a_2}(G_2) + dots + {mathcal{D}}_{a_q}(G_q) + 1$▫. We also show that ▫${mathcal{D}}_{a+b+1}(G) leq {mathcal{D}}_a(F) + {mathcal{D}}_b(B) + 1$▫ if ▫$G$▫ is a graph bundle with fibre ▫$F$▫ over base ▫$B$▫, ▫$a leq k_F$▫, and ▫$b leq k_B$▫. As an auxiliary result we prove that connectivity of graph bundle ▫$G$▫ is at least ▫$k_F+k_B$▫.
Ključne besede: mathematics, graph theory, Cartesian graph bundles, Cartesian graph products, fault diameter, interconnection network
Objavljeno: 10.07.2015; Ogledov: 454; Prenosov: 21
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3. Žerovnik, Janez: On recognition of strong graph bundles. - Math. Slovaca 50 (2000), no. 3, 289-301Sandi Klavžar, 2001, recenzija, prikaz knjige, kritika Ključne besede: matematika, teorija grafov, grafovski svežnji, krepki produkt grafov, algoritem za razpoznavanje, mathematics, graph theory, graph bundles, strong graph product, recognition algorithm
Objavljeno: 10.07.2015; Ogledov: 521; Prenosov: 20
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4. Algorithm for recognizing Cartesian graph bundlesBlaž Zmazek, Janez Žerovnik, 1999, objavljeni povzetek znanstvenega prispevka na konferenci Opis: Grafovski svežnji predstavljajo posplošitev krovnih in produktnih grafov. V članku vpeljemo enolično lokalno produktno relacijo ▫$Delta$▫ na kartezičnih svežnjih nad baznimi grafi, ki ne vsebujejo grafa ▫$K_4 setminus e$▫ in podamo algoritem za razpoznavanje kartezičnih svežnjev nad enostavnimi baznimi grafi brez ▫$K_4 setminus e$▫.
Ključne besede: matematika, teorija grafov, kartezični grafovski svežnji, enolična lokalna produktna lastnost, osnovna faktorizacija, razpoznavanje, polinomski algoritem, mathematics, graph theory, Cartesian graph bundles, unique square property, fundamental factorization, polynomial algorithm, recognition
Objavljeno: 10.07.2015; Ogledov: 531; Prenosov: 65
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5. The edge fault-diameter of Cartesian graph bundlesIztok Banič, Rija Erveš, Janez Žerovnik, 2009, izvirni znanstveni članek Opis: Kartezični svežnji so posplošitev krovnih grafov in kartezičnih grafovskih produktov. Naj bo ▫$G$▫ nek s povezavami ▫$k_G$▫-povezan graf in ▫${bar{mathcal{D}}_c(G)}$▫ največji premer podgrafov grafa ▫$G$▫ dobljenih z odstranitvijo $▫c < k_G$▫ povezav. Dokazano je, da je ▫${bar{mathcal{D}}_{a+b+1}(G)} le {bar{mathcal{D}}_a(F)} le {bar{mathcal{D}}_b(B)} + 1$▫, če je ▫$G$▫ grafovski sveženj z vlaknom ▫$F$▫ in bazo ▫$B$▫, ▫$a < k_F$▫, ▫$b < k_B▫$. Dokazano je tudi, da je povezanost s povezavami grafovskega svežnja ▫$G▫$ vsaj ▫$k_F + k_B$▫.
Ključne besede: matematika, teorija grafov, kartezični grafovski produkti, kartezični grafovski svežnji, povezavni okvarni premer, mathematics, graph theory, Cartesian graph products, Cartesian graph bundles, edge-fault diameter
Objavljeno: 10.07.2015; Ogledov: 661; Prenosov: 65
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6. Recognizing weighted directed Cartesian graph bundlesBlaž Zmazek, Janez Žerovnik, 2000, izvirni znanstveni članek Opis: In this paper we show that methods for recognizing Cartesian graph bundles can be generalized to weighted digraphs. The main result is an algorithm which lists the sets of degenerate arcs for all representations of digraph as a weighted directed Cartesian graph bundle over simple base digraphs not containing transitive tournament on three vertices. Two main notions are used.The first one is the new relation ▫$\vec{\delta}^\ast$▫ defined among the arcs of a digraph as a weighted directed analogue of the well-known relation ▫$\delta^\ast$▫. The second one is the concept of half-convex subgraphs. A subgraph ▫$H$▫ is half-convex in ▫$G$▫ if any vertex ▫$x \in G \setminus H$▫ has at most one predecessor and at most one successor
Ključne besede: mathematics, graph theory, graph bundles, Cartesian graph product, weighted digraphs, half-convexity
Objavljeno: 31.03.2017; Ogledov: 510; Prenosov: 250
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