Relative co-annihilators in lattice equality algebras

. We introduce the notion of relative co-annihilator in lattice equality algebras and investigate some important properties of it. Then, we obtain some interesting relations among ∨ -irreducible filters, positive implicative filters, prime filters and relative co-annihilators. Given a lattice equality algebra E and F a filter of E , we define the set of all F - involutive filters of E and show that by defining some operations on it, it makes a BL-algebra.