A quasi-equational class of \(L\)-algebras is a class of \(L\)-algebras definable using the \(L\)-algebraic language in a slightly more complex way than in equational.classes. A proper \(L\)-quasiequation is a formula of the form \[\bigwedge_{i \le n} \phi_i \approx \psi_i \rightarrow \phi \approx \psi.\] An \(L\)-quasiequation is a formula of the above form but possibly with an empty antecedent, in which case it is just the equation \(\phi \approx \psi\). Hence, the \(L\)-quasiequations are the proper \(L\)-quasiequations and the \(L\)-equations. An \(L\)-quasiequation is valid in an \(L\)-algebra \(\bA\), or the algebra is a model of it, if the universal closure of the quasiequation is sentence true in \(\bA\). A quasi-equational class of \(L\)-algebras is a class of algebras that is the class of the models of a given set of \(L\)-quasiequations. Since equations are quasiequations, every equational class  is quasi-equational. The converse is false. Moreover, since in the trivial algebras all the equations and all the quasiequations of the appropriate algebraic language are valid, equational and  quasi-equational classes are nonempty. 