文摘
Let Mn(B) denote the set of n×n(0,1)-matrices with Boolean arithmetic. The set of primitive matrices of exponent k , denoted Ek, is the set of matrices such that Ak has all nonzero entries and Aj has zero entries for all j<k. For 3≤k≤n, we characterize those linear operators that map Ek to Ek and abf0e1a613bf3a8fc" title="Click to view the MathML source">Ek−1 to abf0e1a613bf3a8fc" title="Click to view the MathML source">Ek−1. We also characterize those linear operators that strongly preserve Ek for 3≤k≤n, that is, that map Ek to Ek and the complement of Ek to the complement of Ek.