Optimizing quadratic forms of adjacency matrices of trees
 
 
Description:  Let G=(V,E) be a tree with n vertices. For n nonnegative numbers x1>= x2 ... >= xn>= 0, there exists a mapping \sigma: V --> {x1,...,xn} which maximizes $\sum \sigma(v)\sigma(w)$, where the sum is over all the edges (v,w) of G . A necessary and sufficient condition is determined for \sigma to be independent of the choice of xi's, and it leads to a corresponding solution for the following problem: Maximize the largest eigenvalue of PDPt+A over a permutation matrix P, where D is a nonnegative diagonal matrix and A is the adjacency matrix of a tree.
Area(s):
Date:  2002-05-22
Start Time:   15:00
Speaker:  Wai-Shun Cheung (Centro de Estruturas Lineares e Combinatórias, Universidade de Lisboa, Portugal)
Place:  Sala 5.5
Research Groups: -Algebra and Combinatorics
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