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\DOC NOT_ELIM
\TYPE {NOT_ELIM : thm -> thm}
\SYNOPSIS
Transforms {|- ~t} into {|- t ==> F}.
\KEYWORDS
rule, implication, negation.
\DESCRIBE
When applied to a theorem {A |- ~t}, the inference rule {NOT_ELIM} returns the
theorem {A |- t ==> F}.
{
A |- ~t
-------------- NOT_ELIM
A |- t ==> F
}
\FAILURE
Fails unless the theorem has a negated conclusion.
\EXAMPLE
{
# let th = UNDISCH(TAUT `p ==> ~ ~p`);;
val th : thm = p |- ~ ~p
# NOT_ELIM th;;
val it : thm = p |- ~p ==> F
}
\SEEALSO
EQF_ELIM, EQF_INTRO, NOT_INTRO.
\ENDDOC
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