(dual) tableau Aristotle's logic Franz Brentano Frege's Zahl-Anzahl distinction Frege's predication scheme Gentzen system Jan Łukasiewicz Kotas' method Kripke models Lewis Carroll Leśniewski's elementary ontology Mathematics & science Peano's axiomatics of natural numbers Peano's axioms Research & information: general Sette's calculus Wilkosz's axioms Wittgenstein Wolniewicz accessibility relation atypical object axiomatic refutation axiomatic system axiomatizations of arithmetic of natural and integers numbers axioms of integer arithmetic modeled on Peano and Wilkosz axioms categoricity completeness concept consistency cut