FIX_TAC : string -> tactic

SYNOPSIS

Fixes universally quantified variables in goal.

DESCRIPTION

Given a string s indicating a sequence of variable names, FIX_TAC s performs the introduction of the indicated universally quantified variables. It is not required to specify the variables in any particular order. The syntax for the string argument s allows the following patterns:

a variable name varname (meaning introduce the variable varname)
a pattern [newname/varname] (meaning introduce varname and call it newname)
a pattern [newname] (meaning introduce the outermost variable and call it newname)
a final * (meaning introduce the remaining outermost universal quantified variables)

FAILURE CONDITIONS

Fails if the string specifying the variables is ill-formed or if some of the indicated variables are not present as outer universal quantifiers in the goal.

EXAMPLE

Here we fix just the variable a:

  # g `!x a. a + x = x + a`;;
  # e (FIX_TAC "a");;
  val it : goalstack = 1 subgoal (1 total)

  `!x. a + x = x + a`

while here we rename one of the variables and fix all the others:

  # g `!a b x. a + b + x = (a + b) + x`;;
  # e (FIX_TAC "[d/x] *");;
  val it : goalstack = 1 subgoal (1 total)

  `a + b + d = (a + b) + d`

Here we fix an automatically generated variable and choose a meaningful name for it

  # g `(@x. x = 0) + 0 = 0`;;
  # e SELECT_ELIM_TAC;;
  val it : goalstack = 1 subgoal (1 total)

  `!_75605. (!x. x = 0 ==> _75605 = 0) ==> _75605 + 0 = 0`

  # e (FIX_TAC "[y]");;
  val it : goalstack = 1 subgoal (1 total)

  `(!x. x = 0 ==> y = 0) ==> y + 0 = 0`