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<p>among the finite Heyting algebras there exist infinitely many that are subdirectly irreducible, no two of which have the same <a href="page.php?w=equational_theory">equational theory</a>. Hence no finite set of finite Heyting algebras can supply all the counterexamples to non-laws of Heyting algebra.  This is in sharp contrast to Boolean algebras, whose only subdirectly irreducible one is the two-element one, which on its own therefore suffices for all counterexamples to non-laws of Boolean algebra, the basis for the simple <a href="page.php?w=truth_table">truth table</a></p><p>
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