Combining intuitionistic connectives and Routley negation

Logic $N^*$ was defined as a logical framework for studying deductive bases of the well founded semantics (WFS) of logics programs with negation. Its semantical definition combines Kripke frames for intuitionistic logic with Routley's $*$-operator, which is used to interpret the negation operation. In this paper we develop algebraic semantics for $N^*$, describe its subdirectly irreducible algebraic models, describe completely the lattice of normal $HT^2$-extensions. The logic $HT^2$ is a finite valued extension of $N^*$, which is a deductive base of WFS. The last result can be used to check the maximality of this deductive base.