2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/153983We investigate the enumeration of varieties of boolean theories related to Horn clauses. We describe a number of combinatorial equivalences among different characterizations and calculate the number of different theories in $n$ variables for slightly different characterizations. The method of counting is via counting models using a satisfiability checker.4 pages, before journal submissionLogic in Computer ScienceDiscrete MathematicsF.4.1text