TRANSPARENT UNIFIERS IN MODAL LOGICS WITH SELF-CONJUGATE OPERATORS
Wojciech Dzik · 2006
It is shown that weakly transitive normal modal logics containing D : }>, with (definable) self-conjugate operators in the sense of Jonsson and Tarski have transparent unifiers, hence, unitary unification. There are continuum many such logics. Transparent unifiers are given in a simple explicit form. In logics with transparent unifiers every admissible rule with unifiable premises is derivable, which is a kind of structural completeness.