 Furthermore, it follows from deep 1998 results of universal algebra by Kearnes and Szendrei in so-called "commutator theory of varieties" that the result above can be extended from the variety of all lattices to any variety formula_9 such that all Con "A", for formula_10, satisfy a fixed nontrivial identity in the signature (∨,∧) (in short, "with a nontrivial congruence identity").We should also mention that many attempts at CLP were also based on the following result, first proved by Bulman-Fleming and McDowell in 1978 by using a categorical 1974 result of Shannon, see also Goodearl and Wehrung in 2001 for a direct argument.Theorem (Bulman-Fleming and McDowell 1978).