variable a : Bool variable b : Bool -- and::introunctions print a && b print a && b && a print a /\ b print a ∧ b print (and a b) print and a b -- Disjunctions print a || b print a \/ b print a ∨ b print (or a b) print or a (or a b) -- Simple Formulas print a → b → a check a → b eval a → a eval true → a -- Simple proof axiom H1 : a axiom H2 : a → b