formal/hol/Help/ABS_TAC.doc

\DOC ABS_TAC

\TYPE {ABS_TAC : tactic}

\SYNOPSIS
Strips an abstraction from each side of an equational goal.

\KEYWORDS
tactic.

\DESCRIBE
{ABS_TAC} reduces a goal of the form {A ?- (\x. s[x]) = (\y. t[y])}
by stripping away the abstractions to give a new goal {A ?- s[x'] = t[x']}
where {x'} is a variant of {x}, the bound variable on the left-hand side,
chosen not to be free in the current goal's assumptions or conclusion.
{
    A ?- (\x. s[x]) = (\y. t[y])
   ================================  ABS_TAC
        A ?- s[x'] = t[x']
}

\FAILURE
Fails unless the goal is equational, with both sides being abstractions.

\SEEALSO
AP_TERM_TAC, AP_THM_TAC, BINOP_TAC, MK_COMB_TAC.

\ENDDOC