Abstract:
On the base of equation calculus, we define the operator of equational closure.
We give examples of equationally complete systems and equationally closed classes.
We find the cardinality of the set of equationally precomplete classes
and give criteria of equational completeness. We present all equationally closed classes
of Boolean functions. This research was supported by the Russian Foundation for Basic Research,
grant 03–01–00783.