The weighted hook length formula

Based on the ideas in Ciocan-Fontanine, Konvalinka and Pak (2009) [5], we introduce the weighted analogue of the branching rule for the classical hook length formula, and give two proofs of this result. The first proof is completely bijective, and in a special case gives a new short combinatorial proof of the hook length formula. Our second proof is probabilistic, generalizing the (usual) hook walk proof of Greene, Nijenhuis and Wilf (1979) [15], as well as the q-walk of Kerov (1993) [20]. Further applications are also presented.     

Symmetry distribution between hook length and part length for partitions

It is known that the two statistics on integer partitions “hook length” and “part length” are equidistributed over the set of all partitions of n. We extend this result by proving that the bivariate joint generating function by those two statistics is symmetric. Our method is based on a generating function by a triple statistic much easier to calculate.     

Finding the largest suborder of fixed width

Finding the largest suborder of fixed width in a partially ordered set is an interesting combinatorial problem with applications in combinatorial optimization and scheduling. We present a polynomial time solution for this problem by transforming it into a minimum cost network flow problem in an appropriate auxiliary network.This research was supported in part by the Natural Sciences and Engineering Research Council of Canada, under Grant No. A1798.     

New hook length formulas for binary trees

We find two new hook length formulas for binary trees. The particularity of our formulas is that the hook length h _v appears as an exponent.     

A multiset hook length formula and some applications

A multiset hook length formula for integer partitions is established by using combinatorial manipulation. As special cases, we rederive three hook length formulas, two of them obtained by Nekrasov–Okounkov, the third one by Iqbal, Nazir, Raza and Saleem, who have made use of the cyclic symmetry of the topological vertex. A multiset hook-content formula is also proved.     

Directed graphs with unique paths of fixed length

We present a solution of the matrix equation A^k = ?I + J, where A is a (0, 1)-matrix.     

Properties of fractional operators with fixed memory length

In this present paper, we discuss some properties of fractional operators with fixed memory length (Riemann–Liouville fractional integral, Riemann–Liouville and Caputo fractional derivatives). Some observations and examples are discussed during the article, in order to make the results well defined and clear. Furthermore, we consider the fundamental theorem of calculus for fractional operators with fixed memory length.     

Partitions with initial repetitions

A variety of interesting connections with modular forms, mock theta functions and Rogers- Ramanujan type identities arise in consideration of partitions in which the smaller integers are repeated as summands more often than the larger summands. In particular, this concept leads to new interpretations of the Rogers Selberg identities and Bailey＇s modulus 9 identities.     

Partitions with k Crossings

We study the number S_k(n) of partitions of the set {1, 2,..., n} with k crossings and show that for each k, their ordinary generating function S_k(x) is a rational function of x and the ordinary generating function of the Catalan numbers. If k = 1, then we get a sequence first found by Cayley in 1890.     

On the largest conjugacy class length of a finite group

Let $G$ be a finite group and $\mathrm{bcl}(G)$ the largest conjugacy class length of $G$ . In this note we slightly improve He and Shi’s lower bound for $\mathrm{bcl}(G)$ , showing that $|\mathrm{bcl}(G)|\ge p^{\frac{1}{p}}(|G:O_{p}(G)|_{p})^{\frac{p-1}{p}}$ .     

Decomposing graphs into paths of fixed length

Barát and Thomassen have conjectured that, for any fixed tree T, there exists a natural number k _T such that the following holds: If G is a k _T -edge-connected graph such that |E(T)| divides |E(G)|, then G has a T-decomposition. The conjecture is trivial when T has one or two edges. Before submission of this paper, the conjecture had been verified only for two other trees: the paths of length 3 and 4, respectively. In this paper we verify the conjecture for each path whose length is a power of 2.     

Quadratic irrationals with fixed period length in the continued fraction expansion

We present an algorithm that makes it possible to write out all quadratic irrationals of the form , that have a given even period length in the continued fraction expansion. It turns out that in the expansion

Approximations for constructing tree-form structures using specific material with fixed length

Substituting for the ordinary objective to minimize the sum of lengths of all edges in some graph structure of a weighted graph, we propose a new problem of constructing certain tree-form structure in same graph, where all edges needed in such a tree-form structure are supposed to be cut from some pieces of a specific material with fixed length. More precisely, we study a new problem defined as follows: a weighted graph \(G=(V,E; w)\), a tree-form structure \(\mathcal{S}\) and some pieces of specific material with length L, where a length function \(w:E\rightarrow Q^+\), satisfying \(w(u,v) \le L\) for each edge uv in G, we are asked how to construct a required tree-form structure \(\mathcal{S}\) as a subgraph \(G'\) of G such that each edge needed in \(G'\) is constructed by a part of a piece of such a specific material, the new objective is to minimize the number of necessary pieces of such a specific material to construct all edges in \(G'\). For this new objective defined, we obtain three results: (1) We present a \(\frac{3}{2}\)-approximation algorithm to construct a spanning tree of G; (2) We design a \(\frac{3}{2}\)-approximation algorithm to construct a single-source shortest paths tree of G; (3) We provide a 4-approximation algorithms to construct a metric Steiner tree of G.     

Partitions with prescribed mean curvatures

We consider a certain variational problem on Caccioppoli partitions with countably many components, which models immiscible fluids as well as variational image segmentation, and generalizes the well-known problem with prescribed mean curvature. We prove existence and regularity results, and finally show some explicit examples of minimizers. Received: 7 June 2001 / Revisied version: 8 October 2001     

Partitions with certain intersection properties

Partitions of the n ‐element set are considered. A family of m such partitions is called an ( n, m, k )‐pamily, if there are two classes for any pair of partitions whose intersection has at least k elements, and any pair of elements is in the same class for at most two partitions. Let f ( n, k ) denote the maximum of m for which an ( n, m, k )‐pamily exist. A constructive lower bound is given for f ( n, k ), which is compared with the trivial upper bound. Copyright © 2011 Wiley Periodicals, Inc. J Combin Designs 19:345‐354, 2011     

On an identity of Glass and Ng concerning the hook length formula

Glass and Ng obtained a simple proof of the hook length formula by establishing an identity on the usage of the residue theorem. In this note we present an algebraic proof of their identity.