UNWIND_CONV : term -> thm

SYNOPSIS

Eliminates existentially quantified variables that are equated to something.

DESCRIPTION

The conversion UNWIND_CONV, applied to a formula with one or more existential quantifiers, eliminates any existential quantifiers where the body contains a conjunct equating its variable to some other term (with that variable not free in it).

FAILURE CONDITIONS

UNWIND_CONV tm fails if tm is not reducible according to that description.

EXAMPLE

  # UNWIND_CONV `?a b c d. b = 7 /\ 2 = d /\ a + b + c + d = 97`;;
  val it : thm =
    |- (?a b c d. b = 7 /\ 2 = d /\ a + b + c + d = 97) <=>
       (?a c. a + 7 + c + 2 = 97)

  # UNWIND_CONV `?w x y z. w = z /\ x = 1 /\ x + y = z /\ y = 42`;;
  val it : thm = |- (?w x y z. w = z /\ x = 1 /\ x + y = z /\ y = 42) <=> T

  # UNWIND_CONV `x = 2`;;
  Exception: Failure "CHANGED_CONV".

SEE ALSO

FORALL_UNWIND_CONV.