IMP_TRANS
Drule.IMP_TRANS : (thm -> thm -> thm)
Implements the transitivity of implication.
When applied to theorems A1 |- t1 ==> t2 and A2 |- t2 ==> t3, the
inference rule IMP_TRANS returns the theorem A1 u A2 |- t1 ==> t3.
A1 |- t1 ==> t2 A2 |- t2 ==> t3
----------------------------------- IMP_TRANS
A1 u A2 |- t1 ==> t3
Failure
Fails unless the theorems are both implicative, with the consequent of the first being the same as the antecedent of the second (up to alpha-conversion).