In this paper, we consider the problem of finding a maximum weight 2-matching containing no cycle of length at most three in a weighted simple graph, which we call the weighted trianglefree 2-matching problem. Although the polynomial solvability of this problem is still open in general graphs, a polynomial-time algorithm is given by Hartvigsen and Li for the problem in subcubic graphs, i.e., gr...

As far as we know, for most polynomially solvable network optimization problems, their inverse problems under l1 or l∞ norm have been studied, except the inverse maximum-weight matching problem in non-bipartite networks. In this paper we discuss the inverse problem of maximum-weight perfect matching in a non-bipartite network under l1 and l∞ norms. It has been proved that the inverse maximum-we...

We define and consider k-distant crossings and nestings for matchings and set partitions, which are a variation of crossings and nestings in which the distance between vertices is important. By modifying an involution of Kasraoui and Zeng (Electronic J. Combinatorics 2006, research paper 33), we show that the joint distribution of k-distant crossings and nestings is symmetric. We also study the...

New formulas for the n moment μn(a, b, c, d; q) of the Askey-Wilson polynomials are given. These are derived using analytic techniques, and by considering three combinatorial models for the moments: Motzkin paths, matchings, and staircase tableaux. A related positivity theorem is given and another one is conjectured. Résumé. Nous présentons de nouvelles formules pour les n-moments μn(a, b, c, d...

Despite numerous efforts extolling the virtues of formal modeling (Epstein 2008; Schank 2001; Smith & Conrey 2007; Marewksi & Olsson 2009; Farrell & Lewandowsky 2010; Weinhardt & Vancouver 2012; Smaldino et al. 2015), there remains widespread resistance among social and behavioral scientists to adopt formal modeling in their general research approach. In addition to the technical challenge pose...

Motivated by Gauss’s first proof of the Fundamental Theorem of Algebra, we study the topology of harmonic algebraic curves. By the maximum principle, a harmonic curve has no bounded components; its topology is determined by the combinatorial data of a noncrossing matching. Similarly, every complex polynomial gives rise to a related combinatorial object that we call a basketball, consisting of a...

We design a fully polynomial time approximation scheme (FPTAS) for counting the number of matchings (packings) in arbitrary 3-uniform hypergraphs of maximum degree three, referred to as (3, 3)hypergraphs. It is the first polynomial time approximation scheme for that problem, which includes also, as a special case, the 3D Matching counting problem for 3-partite (3, 3)-hypergraphs. The proof tech...

The matching energy of a graph is defined as the sum of the absolute values of the zeros of its matching polynomial. Let Gn,m be the set of connected graphs of order n and with m edges. In this note we determined the extremal graphs from Gn,m with n ≤ m ≤ 2n−4 minimizing the matching energy. Also we determined the minimal matching energy of graphs from Gn,m where m = n−1+t and 1 ≤ t ≤ β−1 and w...

Many graph polynomials, such as the Tutte polynomial, the interlace polynomial and the matching polynomial, have both a recursive definition and a defining subset expansion formula. In this article, we present a general, logic-based framework which gives a precise meaning to recursive definitions of graph polynomials. We then prove in this framework that every recursive definition of a graph po...

The matching energy is defined as the sum of the absolute values of the zeros of the matching polynomial of a graph, which is proposed first by Gutman and Wagner [The matching energy of a graph, Discrete Appl. Math. 160 (2012) 2177–2187]. And they gave some properties and asymptotic results of the matching energy. In this paper, we characterize the trees with n vertices whose complements have t...