On odd and semi-odd linear partitions of cubic graphs

Jean-Luc Fouquet; Henri Thuillier; Jean-Marie Vanherpe; Adam P. Wojda

Displaying similar documents to “On odd and semi-odd linear partitions of cubic graphs”

On a family of cubic graphs containing the flower snarks

Jean-Luc Fouquet, Henri Thuillier, Jean-Marie Vanherpe (2010)

Discussiones Mathematicae Graph Theory

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We consider cubic graphs formed with k ≥ 2 disjoint claws $C_{i} K_{1, 3}$ (0 ≤ i ≤ k-1) such that for every integer i modulo k the three vertices of degree 1 of $C_{i}$ are joined to the three vertices of degree 1 of $C_{i - 1}$ and joined to the three vertices of degree 1 of $C_{i + 1}$ . Denote by $t_{i}$ the vertex of degree 3 of $C_{i}$ and by T the set $t ₁, t ₂, . . ., t_{k - 1}$ . In such a way we construct three distinct graphs, namely FS(1,k), FS(2,k) and FS(3,k). The graph FS(j,k) (j ∈ 1,2,3) is the graph where the set of vertices $⋃_{i = 0}^{i = k - 1} V (C_{i}) ∖ T$ induce j cycles (note...

On the order of certain close to regular graphs without a matching of given size

Sabine Klinkenberg, Lutz Volkmann (2007)

Czechoslovak Mathematical Journal

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A graph $G$ is a ${d, d + k}$ -graph, if one vertex has degree $d + k$ and the remaining vertices of $G$ have degree $d$ . In the special case of $k = 0$ , the graph $G$ is $d$ -regular. Let $k, p \geq 0$ and $d, n \geq 1$ be integers such that $n$ and $p$ are of the same parity. If $G$ is a connected ${d, d + k}$ -graph of order $n$ without a matching $M$ of size $2 | M | = n - p$ , then we show in this paper the following: If $d = 2$ , then $k \geq 2 (p + 2)$ and (i) $n \geq k + p + 6$ . If $d \geq 3$ is odd and $t$ an integer with $1 \leq t \leq p + 2$ , then (ii) $n \geq d + k + 1$ for $k \geq d (p + 2)$ , (iii) $n \geq d (p + 3) + 2 t + 1$ for $d (p + 2 - t) + t \leq k \leq d (p + 3 - t) + t - 3$ , (iv) $n \geq d (p + 3) + 2 p + 7$ for $k \leq p$ . If $d \geq 4$ is even, then (v) $n \geq d + k + 2 - η$ for $k \geq d (p + 3) + p + 4 + η$ , (vi) $n \geq d + k + p + 2 - 2 t = d (p + 4) + p + 6$ for $k = d (p + 3) + 4 + 2 t$ and $p \geq 1$ ,...

Some Parity Statistics in Integer Partitions

Aubrey Blecher, Toufik Mansour, Augustine O. Munagi (2015)

Bulletin of the Polish Academy of Sciences. Mathematics

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We study integer partitions with respect to the classical word statistics of levels and descents subject to prescribed parity conditions. For instance, a partition with summands $λ ₁ \geq \dots \geq λ_{k}$ may be enumerated according to descents $λ_{i} > λ_{i + 1}$ while tracking the individual parities of $λ_{i}$ and $λ_{i + 1}$ . There are two types of parity levels, E = E and O = O, and four types of parity-descents, E > E, E > O, O > E and O > O, where E and O represent arbitrary even and odd summands. We obtain functional equations...

Nonempty intersection of longest paths in a graph with a small matching number

Fuyuan Chen (2015)

Czechoslovak Mathematical Journal

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A maximum matching of a graph $G$ is a matching of $G$ with the largest number of edges. The matching number of a graph $G$ , denoted by $α^{'} (G)$ , is the number of edges in a maximum matching of $G$ . In 1966, Gallai conjectured that all the longest paths of a connected graph have a common vertex. Although this conjecture has been disproved, finding some nice classes of graphs that support this conjecture is still very meaningful and interesting. In this short note, we prove that Gallai’s conjecture...

Some results on semi-total signed graphs

Deepa Sinha, Pravin Garg (2011)

Discussiones Mathematicae Graph Theory

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A signed graph (or sigraph in short) is an ordered pair $S = (S^{u}, σ)$ , where $S^{u}$ is a graph G = (V,E), called the underlying graph of S and σ:E → +, - is a function from the edge set E of $S^{u}$ into the set +,-, called the signature of S. The ×-line sigraph of S denoted by $L_{\times} (S)$ is a sigraph defined on the line graph $L (S^{u})$ of the graph $S^{u}$ by assigning to each edge ef of $L (S^{u})$ , the product of signs of the adjacent edges e and f in S. In this paper, first we define semi-total line sigraph and semi-total point sigraph...

Decomposition of Cartesian product of complete graphs into paths and stars with four edges

Arockiajeyaraj P. Ezhilarasi, Appu Muthusamy (2021)

Commentationes Mathematicae Universitatis Carolinae

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Let $P_{k}$ and $S_{k}$ denote a path and a star, respectively, on $k$ vertices. We give necessary and sufficient conditions for the existence of a complete ${P_{5}, S_{5}}$ -decomposition of Cartesian product of complete graphs.

Paired domination in prisms of graphs

Christina M. Mynhardt, Mark Schurch (2011)

Discussiones Mathematicae Graph Theory

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The paired domination number $γ_{p r} (G)$ of a graph G is the smallest cardinality of a dominating set S of G such that ⟨S⟩ has a perfect matching. The generalized prisms πG of G are the graphs obtained by joining the vertices of two disjoint copies of G by |V(G)| independent edges. We provide characterizations of the following three classes of graphs: $γ_{p r} (π G) = 2 γ_{p r} (G)$ for all πG; $γ_{p r} (K ₂ ☐ G) = 2 γ_{p r} (G)$ ; $γ_{p r} (K ₂ ☐ G) = γ_{p r} (G)$ .

Domination and independence subdivision numbers of graphs

Teresa W. Haynes, Sandra M. Hedetniemi, Stephen T. Hedetniemi (2000)

Discussiones Mathematicae Graph Theory

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The domination subdivision number $s d_{γ} (G)$ of a graph is the minimum number of edges that must be subdivided (where an edge can be subdivided at most once) in order to increase the domination number. Arumugam showed that this number is at most three for any tree, and conjectured that the upper bound of three holds for any graph. Although we do not prove this interesting conjecture, we give an upper bound for the domination subdivision number for any graph G in terms of the minimum degrees of...

Unicyclic graphs with bicyclic inverses

Swarup Kumar Panda (2017)

Czechoslovak Mathematical Journal

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A graph is nonsingular if its adjacency matrix $A (G)$ is nonsingular. The inverse of a nonsingular graph $G$ is a graph whose adjacency matrix is similar to $A {(G)}^{- 1}$ via a particular type of similarity. Let $ℋ$ denote the class of connected bipartite graphs with unique perfect matchings. Tifenbach and Kirkland (2009) characterized the unicyclic graphs in $ℋ$ which possess unicyclic inverses. We present a characterization of unicyclic graphs in $ℋ$ which possess bicyclic inverses.

Proper connection number of bipartite graphs

Jun Yue, Meiqin Wei, Yan Zhao (2018)

Czechoslovak Mathematical Journal

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An edge-colored graph $G$ is proper connected if every pair of vertices is connected by a proper path. The proper connection number of a connected graph $G$ , denoted by $pc (G)$ , is the smallest number of colors that are needed to color the edges of $G$ in order to make it proper connected. In this paper, we obtain the sharp upper bound for $pc (G)$ of a general bipartite graph $G$ and a series of extremal graphs. Additionally, we give a proper $2$ -coloring for a connected bipartite graph $G$ having $δ (G) \geq 2$ and a dominating...

On 𝓕-independence in graphs

Frank Göring, Jochen Harant, Dieter Rautenbach, Ingo Schiermeyer (2009)

Discussiones Mathematicae Graph Theory

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Let be a set of graphs and for a graph G let $α_{} (G)$ and $α *_{} (G)$ denote the maximum order of an induced subgraph of G which does not contain a graph in as a subgraph and which does not contain a graph in as an induced subgraph, respectively. Lower bounds on $α_{} (G)$ and $α *_{} (G)$ are presented.

Hamiltonicity of cubic Cayley graphs

Henry Glover, Dragan Marušič (2007)

Journal of the European Mathematical Society

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Following a problem posed by Lovász in 1969, it is believed that every finite connected vertex-transitive graph has a Hamilton path. This is shown here to be true for cubic Cayley graphs arising from finite groups having a $(2, s, 3)$ -presentation, that is, for groups $G = 〈 a, b ∣ a^{2} = 1, b^{s} = 1, {(a b)}^{3} = 1, \dots 〉$ generated by an involution $a$ and an element $b$ of order $s \geq 3$ such that their product $a b$ has order $3$ . More precisely, it is shown that the Cayley graph $X = Cay (G, {a, b, b^{- 1}})$ has a Hamilton cycle when $| G |$ (and thus $s$ ) is congruent to 2 modulo 4, and has a...

Edge-sum distinguishing labeling

Jan Bok, Nikola Jedličková (2021)

Commentationes Mathematicae Universitatis Carolinae

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We study edge-sum distinguishing labeling, a type of labeling recently introduced by Z. Tuza (2017) in context of labeling games. An ESD labeling of an $n$ -vertex graph $G$ is an injective mapping of integers $1$ to $l$ to its vertices such that for every edge, the sum of the integers on its endpoints is unique. If $l$ equals to $n$ , we speak about a canonical ESD labeling. We focus primarily on structural properties of this labeling and show for several classes of graphs if they have or do not...