Example image of eyePlorer eyePlorer map for 'Tautology (logic)': Greek language Interpretation (logic) Propositional calculus Propositional formula Valuation (logic) Ludwig Wittgenstein Philosophy Contradiction Contingency (philosophy) Effective method Truth table Boolean satisfiability problem Computational complexity theory Decision problem NP-complete Tautology (rhetoric) Immanuel Kant Logical truth Gottlob Frege Tractatus Logico-Philosophicus Henri Poincaré Analytic-synthetic distinction Bertrand Russell Conjunction Logical disjunction Negation Law of excluded middle Contraposition Reductio ad absurdum De Morgan's laws Syllogism Proof by exhaustion Deductive system First-order logic Automated theorem proving Recursive set Normal modal logic Law of identity Substitution instance Completeness Craig interpolation Emil Leon Post Intuitionistic logic Logical equivalence Entitative graph Wolfgang Haken Co-NP-complete Status of special relativity Inequation Łukasiewicz logic