On the maximal number of non C - endorigid equivalence relations

Title:	On the maximal number of non C - endorigid equivalence relations
Author:	Ivo Düntsch , Dept of Computer Science , Brock University , St Catherines, Ontario, L2S 3A1, Canada
Status:	Journal of Pure and Applied Algebra 105 (1995), 261 - 265
Abstract:	In [LP] it was shown that a maximal non C - endorigid family of equivalence relations on a set U with \|U\| = n > 2 has at least 2eq(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. [LP] Länger, H., and Pöschel, R. "Relational systems with trivial endomorphisms and polymorphisms", Journal of Pure and Applied Algebra 32 (1984), 129 -- 145.