File: EXISTENCE.doc

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\DOC EXISTENCE

\TYPE {EXISTENCE : (thm -> thm)}

\SYNOPSIS
Deduces existence from unique existence.

\KEYWORDS
rule, unique, existential.

\DESCRIBE
When applied to a theorem with a unique-existentially quantified
conclusion, {EXISTENCE} returns the same theorem with normal existential
quantification over the same variable.
{
    A |- ?!x. p
   -------------  EXISTENCE
    A |- ?x. p
}
\FAILURE
Fails unless the conclusion of the theorem is unique-existentially quantified.

\SEEALSO
EXISTS_UNIQUE_CONV.

\ENDDOC