 We said in  Section 7  that, roughly speaking, a logic \(\bL\) is algebraizable when 1) it has an algebraic semantics, i.e., a class of algebras \(\bK\) and a set of equations \(\iEq(p)\) such that \(\bK\) is a \(\iEq\)-algebraic semantics for \(\bL\), 2) this fact can be proved by using the Lindenbaum-Tarski method slightly generalized and, moreover, 3) \(\bK \subseteq \bAlg^*\bL\). The generalization of the Lindenbaum-Tarski method (as we described it in  Section 7)  consists in allowing in step (5) (as already done in the definition of algebraic semantics) a set of equations \(\iEq(p)\) in one variable instead of a single equation \(\delta(p) \approx \varepsilon(p)\) and in allowing in a similar manner a set of formulas \(\Delta(p, q)\) in at most two variables to play the role of the formula \(p \leftrightarrow q\) in the definition of the congruence of a theory. Then, given a theory \(T\), the relation \(\theta(T)\), which has to be the greatest congruence on the formula algebra compatible with \(T\) (i.e., the Leibniz congruence of \(T)\), is defined by