SELECT_INTRO : (thm -> thm)

SYNOPSIS
Introduces an epsilon term.

DESCRIBE
SELECT_INTRO takes a theorem with an applicative conclusion, say P x, and returns a theorem with the epsilon term $@ P in place of the original operand x.
     A |- P x
   --------------  SELECT_INTRO
    A |- P($@ P)
The returned theorem asserts that $@ P denotes some value at which P holds.

FAILURE
Fails if the conclusion of the theorem is not an application.

EXAMPLE
Given the theorem
   th1 = |- (\n. m = n)m
applying SELECT_INTRO replaces the second occurrence of m with the epsilon abstraction of the operator:
   - val th2 = SELECT_INTRO th1;
   val th2 = |- (\n. m = n)(@n. m = n) : thm
This theorem could now be used to derive a further result:
   - EQ_MP (BETA_CONV(concl th2)) th2;
   val it = |- m = (@n. m = n) : thm

SEEALSO  EXISTS,   SELECT_AX,   SELECT_CONV,   SELECT_ELIM,   SELECT_RULE

HOL  Kananaskis 0