Width sequences for special classes of (0,1)-matrices.:

Abstract : The study of alpha-widths of (0, 1)-matrices (AD-274 181) continued, the emphasis being on those special classes of b by v (0, 1)-matrices having k 1's per row and 4 1's per column. It is assumed throughout that the class parameters b, v, k, r satisfy the inequality (b-r)(v-k-1) less than or equal to v - 1. Such a class has special combinatorial interest. For example, complements of finite projective planes and of Steiner triple systems have parameters satisfying this inequality. Several theorems are proved concerning the width sequence for a matrix in such a class. Insofar as possible, these results are used to obtain information concerning the maximal width sequence for the class. Perhaps the major general result established is that jumps in the width sequence for a matrix in the class, or in the maximal width sequence for the class, are either 1 or 2.