let split = IntroductionTactics.split_tac
let symmetry = EqualityTactics.symmetry_tac
let transitivity = EqualityTactics.transitivity_tac
let split = IntroductionTactics.split_tac
let symmetry = EqualityTactics.symmetry_tac
let transitivity = EqualityTactics.transitivity_tac