We discuss an algebraic approach to propositional logic with side effects. To
this end, we use Hoare's conditional [1985], which is a ternary connective
comparable to if-then-else. Starting from McCarthy's notion of sequential
evaluation [1963] we discuss a number of valuation congruences and we introduce
Hoare-McCarthy algebras as the structures that characterize these congruences.Comment: 29 pages, 1 tabl