A complete characterization of hyperidentities of the variety of weakly idempotent lattices

A hyperidentity is a second order universal formula, i.e., a universal formula from the second order language (in the sense of A. Church and A.I. Mal'tsev). The hyperidentities of the variety of weakly idempotent lattices are completely characterized in this paper. The existence of a finite base of hyperidentities for this variety is proved as a consequence.