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

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