Thanks to Robin Kothari for pointing out the following errors in the
published version of the article:

In the sentence after Theorem 4.2: the O(n^{3/2}) algorithm for Boolean
matrix product verification with operations {OR, AND} is not known to
be optimal. The Omega(n^{3/2}) lower bound holds for matrix product 
verfication over the field GF(2).

Para 3 after Theorem 5.1: the expected time is O(n^{3/2} \sqrt(w)).