 As every congruence of an algebra is the join of the finitely generated congruences below it (e.g., every submodule of a module is the union of all its finitely generated submodules), we obtain the following result, first published by Birkhoff and Frink in 1948.Theorem (Birkhoff and Frink 1948).The congruence lattice Con "A" of any algebra "A" is an algebraic lattice.