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Erfang Shan

Publications and source records attributed to Erfang Shan.

16 recordsLinked to original sources
arXiv2025

A note on the Diversity Owen values

B\'eal et al. (Int J Game Theory 54, 2025) introduce the Diversity Owen value for TU-games with diversity constraints, and provide axiomatic characterizations using the axioms of fairness and balanced contributions. However, there exist logical flaws in the proofs of the uniqueness of these characterizations. In this note we provide the corrected proofs of the characterizations by introducing the null player for diverse games axiom. Also, we establish an alternative characterization of the Diversity Owen value by modifying the axioms of the above characterizations.

econ.TH↗
arXiv2025

Highly mutually dependent unions and new axiomatizations of the Owen value

The Owen value is an well-known allocation rule for cooperative games with coalition structure.In this paper, we introduce the concept of highly mutually dependent unions. Two unions in a cooperative game with coalition structure are said to be highly mutually dependent if any pair of players, with one from each of the two unions, are mutually dependent in the game.Based on this concept, we introduce two axioms: weak mutually dependent between unions and differential marginality of inter-mutually dependent unions. Furthermore, we also propose another two axioms: super inter-unions marginality and invariance across games, where the former one is based on the concept of the inter-unions marginal contribution. By using the axioms and combining with some standard axioms, we present three axiomatic characterizations of the Owen value.

econ.TH↗
arXiv2021

Anti-Ramsey number of matchings in $r$-partite $r$-uniform hypergraphs

An edge-colored hypergraph is rainbow if all of its edges have different colors. Given two hypergraphs $\mathcal{H}$ and $\mathcal{G}$, the anti-Ramsey number $ar(\mathcal{G}, \mathcal{H})$ of $\mathcal{H}$ in $\mathcal{G}$ is the maximum number of colors needed to color the edges of $\mathcal{G}$ so that there does not exist a rainbow copy of $\mathcal{H}$. Li et al. determined the anti-Ramsey number of $k$-matchings in complete bipartite graphs. Jin and Zang showed the uniqueness of the extremal coloring. In this paper, as a generalization of these results, we determine the anti-Ramsey number $ar_r(\mathcal{K}_{n_1,\ldots,n_r},M_k)$ of $k$-matchings in complete $r$-partite $r$-uniform hypergraphs and show the uniqueness of the extremal coloring. Also, we show that $\mathcal{K}_{k-1,n_2,\ldots,n_r}$ is the unique extremal hypergraph for Turán number $ex_r(\mathcal{K}_{n_1,\ldots,n_r},M_k)$ and show that $ar_r(\mathcal{K}_{n_1,\ldots,n_r},$ $M_k)=ex_r(\mathcal{K}_{n_1,\ldots,n_r},M_{k-1})+1$, which gives a multi-partite version result of Özkahya and Young's conjecture.

math.CO↗
arXiv2018

The matching polynomials and spectral radii of uniform supertrees

We study matching polynomials of uniform hypergraph and spectral radii of uniform supertrees. By comparing the matching polynomials of supertrees, we extend Li and Feng's results on grafting operations on graphs to supertrees. Using the methods of grafting operations on supertrees and comparing matching polynomials of supertrees, we determine the first $\lfloor\frac{d}{2}\rfloor+1$ largest spectral radii of $r$-uniform supertrees with size $m$ and diameter $d$. In addition, the first two smallest spectral radii of supertrees with size $m$ are determined.

math.CO↗
arXiv2018

On the irregularity of uniform hypergraphs

Let $H$ be an $r$-uniform hypergraph on $n$ vertices and $m$ edges, and let $d_i$ be the degree of $i\in V(H)$. Denote by $\varepsilon(H)$ the difference of the spectral radius of $H$ and the average degree of $H$. Also, denote \[ s(H)=\sum_{i\in V(H)}\left|d_i-\frac{rm}{n}\right|,~ v(H)=\frac{1}{n}\sum_{i\in V(H)}d_i^{\frac{r}{r-1}}-\left(\frac{rm}{n}\right)^{\frac{r}{r-1}}. \] In this paper, we investigate the irregularity of $r$-uniform hypergraph $H$ with respect to $\varepsilon(H)$, $s(H)$ and $v(H)$, which extend relevant results to uniform hypergraphs.

math.CO↗
arXiv2017

Domination in intersecting hypergraphs

A matching in a hypergraph $H$ is a set of pairwise disjoint hyperedges. The matching number $α'(H)$ of $H$ is the size of a maximum matching in $H$. A subset $D$ of vertices of $H$ is a dominating set of $H$ if for every $v\in V\setminus D$ there exists $u\in D$ such that $u$ and $v$ lie in an hyperedge of $H$. The cardinality of a minimum dominating set of $H$ is called the domination number of $H$, denoted by $γ(H)$. It is known that for a intersecting hypergraph $H$ with rank $r$, $γ(H)\leq r-1$. In this paper we present structural properties on intersecting hypergraphs with rank $r$ satisfying the equality $γ(H)=r-1$. By applying the properties we show that all linear intersecting hypergraphs $H$ with rank $4$ satisfying $γ(H)=r-1$ can be constructed by the well-known Fano plane.

math.CO↗
arXiv2016

Sharp lower bounds on the spectral radius of uniform hypergraphs concerning degrees

Let $\mathcal{A}(H)$ and $\mathcal{Q}(H)$ be the adjacency tensor and signless Laplacian tensor of an $r$-uniform hypergraph $H$. Denote by $ρ(H)$ and $ρ(\mathcal{Q}(H))$ the spectral radii of $\mathcal{A}(H)$ and $\mathcal{Q}(H)$, respectively. In this paper we present a lower bound on $ρ(H)$ in terms of vertex degrees and we characterize the extremal hypergraphs attaining the bound, which solves a problem posed by Nikiforov [V. Nikiforov, Analytic methods for uniform hypergraphs, Linear Algebra Appl. 457 (2014) 455-535]. Also, we prove a lower bound on $ρ(\mathcal{Q}(H))$ concerning degrees and give a characterization of the extremal hypergraphs attaining the bound.

math.SP↗
arXiv2016

Extremal hypergraphs for matching number and domination number

A matching in a hypergraph $\mathcal{H}$ is a set of pairwise disjoint hyperedges. The matching number $ν(\mathcal{H})$ of $\mathcal{H}$ is the size of a maximum matching in $\mathcal{H}$. A subset $D$ of vertices of $\mathcal{H}$ is a dominating set of $\mathcal{H}$ if for every $v\in V\setminus D$ there exists $u\in D$ such that $u$ and $v$ lie in an hyperedge of $\mathcal{H}$. The cardinality of a minimum dominating set of $\mathcal{H}$ is the domination number of $\mathcal{H}$, denoted by $γ(\mathcal{H})$. It was proved that $γ(\mathcal{H})\leq (r-1)ν(\mathcal{H})$ for $r$-uniform hypergraphs and the 2-uniform hypergraphs (graphs) achieving equality $γ(\mathcal{H})=ν(\mathcal{H})$ have been characterized. In this paper we generalize the inequality $γ(\mathcal{H})\leq (r-1)ν(\mathcal{H})$ to arbitrary hypergraph of rank $r$ and we completely characterize the extremal hypergraphs $\mathcal{H}$ of rank $3$ achieving equality $γ(\mathcal{H})=(r-1)ν(\mathcal{H})$.

math.CO↗
arXiv2016

Total domination polynomials of graphs

Given a graph $G$, a total dominating set $D_t$ is a vertex set that every vertex of $G$ is adjacent to some vertices of $D_t$ and let $d_t(G,i)$ be the number of all total dominating sets with size $i$. The total domination polynomial, defined as $D_t(G,x)=\sum\limits_{i=1}^{| V(G)|} d_t(G,i)x^i$, recently has been one of the considerable extended research in the field of domination theory. In this paper, we obtain the vertex-reduction and edge-reduction formulas of total domination polynomials. As consequences, we give the total domination polynomials for paths and cycles. Additionally, we determine the sharp upper bounds of total domination polynomials for trees and characterize the corresponding graphs attaining such bounds. Finally, we use the reduction-formulas to investigate the relations between vertex sets and total domination polynomials in $G$.

math.CO↗
arXiv2016

Characterizations of the position value for hypergraph communication situations

The Mayser value (Myerson (1977)), the position value (Meessen (1988)) and the average tree solution (Herings et al.) are three most important allocation rules for (graph or hypergraph) communication situations. In 2005, an axiomatic characterization of the position value for arbitrary (graph) communication situations was given by Slikker (2005). However, an axiomatic characterization of the position value for arbitrary hypergraph communication situations has not yet been found and remains an open problem. In our manuscript, we first give two non-axiomatic characterizations of the position value for hypergraph communication situations by introducing the uniform hyperlink game and the $k$-augment uniform hyperlink game. Based on the non-axiomatic characterizations, we provide an axiomatic characterization of the position value for arbitrary hypergraph communication situations by employing component efficiency and partial balanced conference contributions.

math.OC↗
arXiv2015

Matching criticality in intersecting hypergraphs

A matching in a hypergraph $H$ is a set of pairwise vertex disjoint edges in $H$ and the matching number of $H$ is the maximum cardinality of a matching in $H$. A transversal in $H$ is a subset of vertices in $H$ that has a nonempty intersection with every edge of $H$. The transversal number $τ(H)$ of $H$ is the minimum cardinality of a transversal in $H$. A hypergraph $H$ is an intersecting hypergraph if every two distinct edges of $H$ have a non-empty intersection. Equivalently, $H$ is an intersecting hypergraph if and only if it has matching number one. In this paper we study the extremal behavior of matching critical intersecting hypergraphs. We partly solve an open problem on matching critical intersecting hypergraphs posed by Henning and Yeo. We also prove a strengthening of the result for intersecting $r$-uniform hypergraphs.

math.CO↗
arXiv2015

The distance domination of generalized de Bruijn and Kautz digraphs

Let $G=(V,A)$ be a digraph and $k\ge 1$ an integer. For $u,v\in V$, we say that the vertex $u$ distance $k$-dominate $v$ if the distance from $u$ to $v$ at most $k$. A set $D$ of vertices in $G$ is a distance $k$-dominating set if for each vertex of $V\setminus D$ is distance $k$-dominated by some vertex of $D$. The {\em distance $k$-domination number} of $G$, denoted by $γ_{k}(G)$, is the minimum cardinality of a distance $k$-dominating set of $G$. Generalized de Bruijn digraphs $G_B(n,d)$ and generalized Kautz digraphs $G_K(n,d)$ are good candidates for interconnection networks. Tian and Xu showed that $\big \lceil n\big/\sum_{j=0}^kd^j\big\rceil\le γ_{k}(G_B(n,d))\le \big\lceil n/d^{k}\big\rceil$ and $\big \lceil n \big/\sum_{j=0}^kd^j\big\rceil\le γ_{k}(G_K(n,d))\le \big\lceil n/d^{k}\big\rceil$. In this paper we prove that every generalized de Bruijn digraph $G_B(n,d)$ has the distance $k$-domination number $\big\lceil n\big/\sum_{j=0}^kd^j\big\rceil$ or $\big\lceil n\big/\sum_{j=0}^kd^j\big\rceil+1$, and the distance $k$-domination number of every generalized Kautz digraph $G_K(n,d)$ bounded above by $\big\lceil n\big/(d^{k-1}+d^{k})\big\rceil$. Additionally, we present various sufficient conditions for $γ_{k}(G_B(n,d))=\big\lceil n\big/\sum_{j=0}^kd^j\big\rceil$ and $γ_{k}(G_K(n,d))=\big\lceil n\big/\sum_{j=0}^kd^j\big\rceil$.

math.CO↗
arXiv2014

Coloring clique-hypergraph of $K_5$-minor-free graphs

A clique-coloring of a graph $G$ is a coloring of the vertices of $G$ so that no maximal clique of size at least two is monochromatic. The clique-hypergraph, $\mathcal{H}(G)$, of a graph $G$ has $V(G)$ as its set of vertices and the maximal cliques of $G$ as its hyperedges. A (vertex) coloring of $\mathcal{H}(G)$ is a clique-coloring of $G$. The clique-chromatic number of $G$ is the least number of colors for which $G$ admits a clique-coloring. Every planar graph has been proved to be 3-clique-colorable (Electr. J. Combin. 6 (1999), \#R26). Recently, we showed that every claw-free planar graph, different from an odd cycle, is $2$-clique-colorable (European J. Combin. 36 (2014) 367-376). In this paper we generalize these results to \{claw, $K_5$-minor\}-free graphs.

math.CO↗
arXiv2014

3-Factor-criticality in double domination edge critical graphs

A vertex subset $S$ of a graph $G$ is a double dominating set of $G$ if $|N[v]\cap S|\geq 2$ for each vertex $v$ of $G$, where $N[v]$ is the set of the vertex $v$ and vertices adjacent to $v$. The double domination number of $G$, denoted by $γ_{\times 2}(G)$, is the cardinality of a smallest double dominating set of $G$. A graph $G$ is said to be double domination edge critical if $γ_{\times 2}(G+e)<γ_{\times 2}(G)$ for any edge $e \notin E$. A double domination edge critical graph $G$ with $γ_{\times 2}(G)=k$ is called $k$-$γ_{\times 2}(G)$-critical. A graph $G$ is $r$-factor-critical if $G-S$ has a perfect matching for each set $S$ of $r$ vertices in $G$. In this paper we show that $G$ is 3-factor-critical if $G$ is a 3-connected claw-free $4$-$γ_{\times 2}(G)$-critical graph of odd order with minimum degree at least 4 except a family of graphs.

math.CO↗