DISCH_TAC : tactic

SYNOPSIS
Moves the antecedent of an implicative goal into the assumptions.

DESCRIBE
    A ?- u ==> v
   ==============  DISCH_TAC
    A u {u} ?- v
Note that DISCH_TAC treats ~u as u ==> F, so will also work when applied to a goal with a negated conclusion.

FAILURE
DISCH_TAC will fail for goals which are not implications or negations.

USES
Solving goals of the form u ==> v by rewriting v with u, although the use of DISCH_THEN is usually more elegant in such cases.

COMMENTS
If the antecedent already appears in the assumptions, it will be duplicated.

SEEALSO  DISCH,   DISCH_ALL,   DISCH_THEN,   FILTER_DISCH_TAC,   FILTER_DISCH_THEN,   NEG_DISCH,   STRIP_TAC,   UNDISCH,   UNDISCH_ALL,   UNDISCH_TAC

HOL  Kananaskis 0