Axiomatic system11 exercisesAn axiomatic system is a triple S=(L,A,R) made of a formal language, axioms and rules of inference.
Rule of inference10 exercisesA rule of inference authorizes the formal step from the premises φ_1,…,φ_n to the conclusion ψ.
Modus ponens11 exercisesLet P and Q be propositions. Modus ponens allows concluding Q from P⇒ Q and P.
Formal proof10 exercisesA formal proof of φ_n is a sequence φ_1,…,φ_n in which each term is an axiom, an admitted hypothesis, or the result of a rule app…
Consistency10 exercisesA system S is consistent if there is no formula φ such that S proves both φ and ¬φ.