India TST : Day4 :Problem 3
Source: medium
May 22, 2009
combinatorics proposedcombinatorics
Problem Statement
Let be a simple graph with vertex set V\equal{}\{0,1,2,3,\cdots ,n\plus{}1\} .and j\plus{}1 are connected by an edge for . Let be a subset of and be the induced subgraph associated with . Let be number of components of having an odd number of vertices.
Let
T(p,r)\equal{}\{A\subset V \mid 0.n\plus{}1 \notin A,|A|\equal{}p,O(G(A))\equal{}2r\} for .
Prove That |T(p,r)|\equal{}{n\minus{}r \choose{p\minus{}r}}{n\minus{}p\plus{}1 \choose{2r\minus{}p}}.