(***************************************************************************)
(* Formalization of the Chou, Gao and Zhang's decision procedure.          *)
(* Julien Narboux (Julien@narboux.fr)                                      *)
(* LIX/INRIA FUTURS 2004-2006                                              *)
(* University of Strasbourg 2008                                           *)
(***************************************************************************)
Require Export geometry_tools_lemmas.
Require Export my_field_tac.
(***********************************************)
(* Unification tactic for signed areas         *)
(***********************************************)
(* Simplification is necessary for termination *)
(***********************************************)
Ltac uniformize_signed_areas_goal :=
repeat
match goal with
|  |- context [(- - ?X1)] =>
replace (- - X1) with X1 by apply simplring1
|  |- context [(S ?X1 ?X1 ?X2)] =>
replace (S X1 X1 X2) with 0 by apply trivial_col1
|  |- context [(S ?X2 ?X1 ?X1)] =>
replace (S X2 X1 X1) with 0 by apply trivial_col2
|  |- context [(S ?X1 ?X2 ?X1)] =>
replace (S X1 X2 X1) with 0 by apply trivial_col3
|  |- context [(S ?X1 ?X2 ?X3)] =>
( let Truc := fresh in
match goal with
|  |- context [(S ?X4 ?X5 ?X6)] =>
(assert (Truc : S X4 X5 X6 = - S X1 X2 X3);
[ apply S_3 || apply S_2 || apply S_4
| rewrite Truc; clear Truc ]) ||
(assert (Truc : S X4 X5 X6 = S X1 X2 X3);
[ apply S_0 || apply S_1 | rewrite Truc; clear Truc ])
end)
end.
Ltac generalize_all_areas :=
repeat match goal with
H: context [(S ?X1 ?X2 ?X3)] |- _=> revert H
end.
Ltac uniformize_signed_areas :=
generalize_all_areas;uniformize_signed_areas_goal;intros.
intros.
unfold S4 in |- *.
uniformize_signed_areas.
ring.
Qed.
intros.
unfold S4 in |- *.
uniformize_signed_areas.
ring.
Qed.
intros.
unfold S4 in |- *.
uniformize_signed_areas.
ring.
Qed.
intros.
unfold S4 in |- *.
uniformize_signed_areas.
ring.
Qed.
Ltac uniformize_signed_areas4_goal :=
repeat
match goal with
|  |- context [(- - ?X1)] =>
replace (- - X1) with X1; [ idtac | apply simplring1 ]
|  |- context [(S4 ?X1 ?X2 ?X1 ?X3)] =>
rewrite (S4Simpl_6 X1 X2 X3)
|  |- context [(S4 ?X2 ?X1 ?X3 ?X1)] =>
rewrite (S4Simpl_5 X1 X2 X3)
|  |- context [(S4 ?X1 ?X2 ?X2 ?X3)] =>
rewrite (S4Simpl_1 X1 X2 X3)
|  |- context [(S4 ?X1 ?X2 ?X3 ?X3)] =>
rewrite (S4Simpl_2 X1 X2 X3)
|  |- context [(S4 ?X1 ?X1 ?X2 ?X3)] =>
rewrite (S4Simpl_3 X1 X2 X3)
|  |- context [(S4 ?X1 ?X2 ?X3 ?X1)] =>
rewrite (S4Simpl_4 X1 X2 X3)
|  |- context [(S4 ?X1 ?X2 ?X3 ?X4)] =>
match goal with
|  |- context [(S4 ?X5 ?X6 ?X7 ?X8)] =>
(assert (Truc : S4 X5 X6 X7 X8 = - S4 X1 X2 X3 X4);
[ apply S4_5 || apply S4_6 || apply S4_7 || apply S4_8
| rewrite Truc; clear Truc ]) ||
(assert (Truc : S4 X5 X6 X7 X8 = S4 X1 X2 X3 X4);
[ apply S4_2 || apply S4_3 || apply S4_4
| rewrite Truc; clear Truc ])
end
end.
Ltac generalize_all_areas4 :=
repeat match goal with
H: context [(S4 ?X1 ?X2 ?X3 ?X4)] |- _=> revert H
end.
Ltac uniformize_signed_areas4 :=
generalize_all_areas4;uniformize_signed_areas4_goal;intros.
(****************************************)
(* Signed distance unification tactic   *)
(****************************************)
Ltac uniformize_dir_seg_goal :=
repeat
match goal with
|  |- context [(- - ?X1)] =>
replace (- - X1) with X1; [ idtac | apply simplring1 ]
|  |- context [(?X1 ** ?X1)] =>
rewrite <- (nuldirseg X1)
|  |- context [(?X1 ** ?X2)] =>
match goal with
|  |- context [(?X3 ** ?X4)] =>
match constr:((X3, X4)) with
| (?X2, ?X1) => rewrite (A1a X1 X2)
end
end
end.
Ltac generalize_all_seg :=
repeat match goal with
H: context [(?X1 ** ?X2)] |- _=> revert H
end.
Ltac uniformize_dir_seg_general :=
generalize_all_seg;uniformize_dir_seg_goal;intros.
Ltac try_rw A B := try rewrite <- (A1a B A) in *;
try rewrite    (A1a A B) in *.
Ltac uniformize_dir_seg_spec := match reverse goal with
| [A : Point, B : Point, C : Point,
D : Point, E : Point, F : Point,
G : Point |- _ ] => fail 1
| [A : Point, B : Point, C : Point, D: Point, E: Point, F: Point |- _ ] =>
try_rw A B; try_rw A C; try_rw A D; try_rw A E; try_rw A F;
try_rw B C; try_rw B D; try_rw B E; try_rw B F;
try_rw C D; try_rw C E; try_rw C F;
try_rw D E; try_rw D F;
try_rw E F
| [A : Point, B : Point, C : Point, D: Point, E: Point |- _ ] =>
try_rw A B; try_rw A C; try_rw A D; try_rw A E;
try_rw B C; try_rw B D; try_rw B E;
try_rw C D; try_rw C E;
try_rw D E
| [A : Point, B : Point, C : Point, D: Point |- _ ] =>
try_rw A B; try_rw A C; try_rw A D; try_rw B C; try_rw B D; try_rw C D
| [A : Point, B : Point, C : Point |- _ ] =>
try_rw A B; try_rw A C;try_rw B C
| [A : Point, B : Point |- _ ] =>
try_rw A B
end.
Ltac uniformize_dir_seg := uniformize_dir_seg_spec || uniformize_dir_seg_general.

Lemma test_uniformize_dir_seg_2 : forall A B,
A ** B = - B**A ->
A ** B = - B**A.