Two injective proofs of a conjecture of Simion

A Simple Proof of a Conjecture of Simion

Simion had a unimodality conjecture concerning the number of lattice paths in a rectangular grid with the Ferrers diagram of a partition removed. Hildebrand recently showed the stronger result that these numbers are log concave. Here we present a simple proof of Hildebrand's result.

e-内射着色：内射着色与2-距离着色猜想

e-injective coloring: injective and 2-distance colorings conjectures

该研究提出e-内射着色的新定义，将其与普通着色、内射着色、2-距离着色对比，从新视角回顾相关着色猜想，并精确分析了多类图的e-内射着色性质。

Unimodality and the reflection principle

We show how lattice paths and the reflection principle can be used to give easy proofs of unimodality results. In particular, we give a "one-line" combinatorial proof of the unimodality of the binomial coefficients. Other examples include products of binomial coefficients, polynomials related to the Legendre polynomials, and a result connected to a conjecture of Simion.

Pairs of a tree and a nontree graph with the same status sequence

The status of a vertex $x$ in a graph is the sum of the distances between $x$ and all other vertices. Let $G$ be a connected graph. The status sequence of $G$ is the list of the statuses of all vertices arranged in nondecreasing order. $G$ is called status injective if all the statuses of its vertices are distinct. Let $G$ be a member of a family of graphs $\mathscr{F}$ and let the status sequence of $G$ be $s.$ $G$ is said to be status unique in $\mathscr{F}$ if $G$ is the unique graph in $\mathscr{F}$ whose status sequence is $s.$ In 2011, J.L. Shang and C. Lin posed the following two conjec…

给定单射色数的无限族平面图

Infinite families of planar graphs of a given injective chromatic number

本研究通过计算验证与无限族3-连通平面图构造，拓展了平面图单射着色相关猜想的研究成果，给出多个经典猜想的无限反例并为修正猜想提供支撑。

初等对称多项式与一个可能的单射映射家族在整数划分上的应用

Elementary symmetric polynomials and a potentially injective family of maps on partitions

本文通过无限例证反驳Ballantine及其合作者关于整数划分上pre_k映射单射性的猜想，研究了这些映射间的相互关系，并提供了三种子情况的替代证明。