On the maximal number of non-C-endorigid equivalence relations Original Research Article

In [1] it was shown that a maximal non-C-endorigid family of equivalence relations on a set U with ¦U¦ = n ≥ 3 has at least 2·eq(n − 1) elements, where eq(m) is the number of equivalence relations on a set with m elements, and it was asked whether any larger family of such relations exists. In this note we show that the given bound is the best possible.