An efficient algorithm for the minimal unsatisfiability problem for a subclass of CNF

We consider the minimal unsatisfiability problem for propositional formulas over n variables with n+k clauses for fixedk. We will show that in case of at most n clauses no formula is minimal unsatisfiable. For n+1 clauses the minimal unsatisfiability problem is solvable in quadratic time. Further, we present a characterization of minimal unsatisfiable formulas with n+1clauses in terms of a certain form of matrices.