 Let \(\bL\) be one of the logics discussed in the examples in  Section 5.  Let \(\bK\) be the corresponding class of algebras we considered there and let \(\delta(p) \approx \varepsilon(p)\) be the equation in one variable involved in the soundness and completeness theorem. To prove the completeness theorem one proceeds as follows. Given any set of formulas \(\Gamma\):