finitely definable quasivariety

См. также в других словарях:

• Pseudoelementary class — In logic, a pseudoelementary class is a class of structures derived from an elementary class (one definable in first order logic) by omitting some of its sorts and relations. It is the mathematical logic counterpart of the notion in category… …   Wikipedia

• Relation algebra — is different from relational algebra, a framework developed by Edgar Codd in 1970 for relational databases. In mathematics, a relation algebra is a residuated Boolean algebra supporting an involutary unary operation called converse. The… …   Wikipedia