MESON_TAC : thm list -> tactic
STRUCTURE
SYNOPSIS
Performs first order proof search to prove the goal, using the given theorems as additional assumptions in the search.
LIBRARY
mesonLib
DESCRIPTION
MESON_TAC performs first order proof using the model elimination algorithm. This algorithm is semi-complete for pure first order logic. It makes special provision for handling polymorphic and higher-order values, and often this is sufficient. It does not handle conditional expressions at all, and these should be eliminated before MESON_TAC is applied.

MESON_TAC works by first converting the problem instance it is given into an internal format where it can do proof search efficiently, without having to do proof search at the level of HOL inference. If a proof is found, this is translated back into applications of HOL inference rules, proving the goal.

The feedback given by MESON_TAC is controlled by the level of the integer reference variable mesonLib.chatting. At level zero, nothing is printed. At the default level of one, a line of dots is printed out as the proof progresses. At all other values for this variable, MESON_TAC is most verbose. If the proof is progressing quickly then it is often worth waiting for it to go quite deep into its search. Once a proof slows down, it is not usually worth waiting for it after it has gone through a few (no more than five or six) levels. (At level one, a “level” is represented by the printing of a single dot.)

FAILURE
MESON_TAC fails if it searches to a depth equal to the contents of the reference variable mesonLib.max_depth (set to 30 by default, but changeable by the user) without finding a proof. Shouldn’t fail otherwise.

USES
MESON_TAC can only progress the goal to a successful proof of the (whole) goal or not at all. In this respect it differs from tactics such as simplification and rewriting. Its ability to solve existential goals and to make effective use of transitivity theorems make it a particularly powerful tactic.

COMMENTS
The assumptions of a goal are ignored when MESON_TAC is applied. To include assumptions use ASM_MESON_TAC.

SEEALSO
HOL  Kananaskis-10