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1 vote
1 answer
165 views

Combinatorial graph optimization problem on integer adjacency matrices

We are given a $n\times n$ symmetric matrix $M$ whose entries are positive integers. Let $z_{i,j}:=\frac{M_{i,j}}{M_{i,j}+\sum_{k\neq i,j}\min(M_{i,k},M_{k,j})}$ for all $1\le i<j \le n$, and $z:=\...
5 votes
1 answer
171 views

Graph combinatorial optimization problem

Let $G$ be a simple graph with vertex set $V$, such that for any two vertices $u,v\in V$, we have at least $k$ edge-disjoint paths of length $2$ (i.e., formed by $2$ edges) connecting $u$ with $v$. ...
2 votes
1 answer
155 views

Combinatorial process on multisets of integers

Edit: I prefer to formulate first the problem as Fedor Petrov suggests in the comments: We are given a multiset $F$, initially containing only the single integer $h$. Sequentially, at each time step, ...
2 votes
0 answers
108 views

What is the optimal upper bound of $|T_1|+|T_2|+|T_3|$ if $T_1, T_2, T_3$ are trees covering a planar graph

By a classical theorem of Nash-Williams, the edges of every connected $n$-vertex planar graph can be covered by three trees $T_1,T_2$ and $T_3$. Does anyone know of any results from an article or a ...
3 votes
1 answer
305 views

Counting the forests obtainable by removing subtrees from binary trees

Let $B_h$ be the perfect binary tree having height $h$ (i.e. the binary tree with height $h$ in which all interior nodes have two children and all leaves have the same depth or same level). For any ...
2 votes
1 answer
164 views

Combinatorial optimization for a sequential random process on graphs

Let $G(V, E)$ be a simple graph with $|V|=n$, and let $h$ be an integer in $[n]$. We repeat $h$-many times the following operation in a sequential fashion, where the graph may change at each round. ...