English

Multivalued matrices and forbidden configurations

Combinatorics 2017-10-03 v1

Abstract

An rr-matrix is a matrix with symbols in {0,1,,r1}\{0,1,\ldots,r-1\}. A matrix is simple if it has no repeated columns. Let F{\cal F} be a finite set of rr-matrices. Let forb(m,r,F)\hbox{forb}(m,r,{\cal F}) denote the maximum number of columns possible in a simple rr-matrix AA that has no submatrix which is a row and column permutation of any FFF\in{\cal F}. Many investigations have involved r=2r=2. For general rr, forb(m,r,F)\hbox{forb}(m,r,{\cal F}) is polynomial in mm if and only if for every pair i,j{0,1,,r1}i,j\in\{0,1,\ldots,r-1\} there is a matrix in F{\cal F} whose entries are only ii or jj. Let T(r){\cal T}_{\ell}(r) denote the following rr-matrices. For a pair i,j{0,1,,r1}i,j\in\{0,1,\ldots,r-1\} we form four ×\ell\times\ell matrices namely the matrix with ii's on the diagonal and jj's off the diagonal and the matrix with ii's on and above the diagonal and jj's below the diagonal and the two matrices with the roles of i,ji,j reversed. Anstee and Lu determined that forb(m,r,T(r))\hbox{forb}(m,r,{\cal T}_{\ell}(r)) is a constant. Let F{\cal F} be a finite set of 2-matrices. We ask if forb(m,r,T(3)\T(2)F)\hbox{forb}(m,r,{\cal T}_{\ell}(3)\backslash {\cal T}_{\ell}(2)\cup {\cal F}) is Θ(forb(m,2,F))\Theta(\hbox{forb}(m,2,{\cal F})) and settle this in the affirmative for some cases including most 2-columned FF.

Keywords

Cite

@article{arxiv.1710.00374,
  title  = {Multivalued matrices and forbidden configurations},
  author = {Richard Anstee and Jeffrey Dawson and Linyuan Lu and Attila Sali},
  journal= {arXiv preprint arXiv:1710.00374},
  year   = {2017}
}
R2 v1 2026-06-22T22:00:13.575Z