DISJ1_TAC : tactic
STRUCTURE
SYNOPSIS
Selects the left disjunct of a disjunctive goal.
DESCRIPTION
   A ?- t1 \/ t2
  ===============  DISJ1_TAC
     A ?- t1

FAILURE
Fails if the goal is not a disjunction.
SEEALSO
HOL  Kananaskis-10