(***************************************************************************)
(* 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.
Proof with try solve [ ring | congruence ].
intros.
assert (- -a=-0).
rewrite H...
assert (- -a=a)...
assert (-0=0)...
Qed.
Hint Resolve field_prop1 : Geom.
(** Some propositions about Col *)
Proof with uniformize_signed_areas;Geometry.
unfold Col in |- *.
intros...
Qed.
Proof with uniformize_signed_areas;Geometry.
unfold Col in |- *.
intros...
Qed.
Proof with uniformize_signed_areas;Geometry.
unfold Col in |- *.
intros...
Qed.
Proof with uniformize_signed_areas;Geometry.
unfold Col in |- *.
intros...
Qed.
Proof with uniformize_signed_areas;Geometry.
unfold Col in |- *.
intros...
Qed.
Hint Resolve col_1 col_2 col_3 col_4 col_5: Geom.
(** Proposition about equality and nullity of geometric quantities *)
intros.
assert (A ** B = 0 <-> A = B).
apply A1b.
intuition.
Qed.
Hint Resolve noteqnotzero: Geom.
Proof with try solve [ Geometry | congruence ].
intros.
unfold Col.
rewrite H...
Qed.
unfold Col in |- *.
intros.
intuition.
assert (T := egalcol A B C H0).
auto.
Qed.
intros.
assert (~ Col A B C -> ~ Col B C A).
intuition.
assert (~ Col B C A).
auto.
eapply notcolnotegal_1.
apply H1.
Qed.
intros.
assert (~ Col A B C -> ~ Col A C B).
intuition.
assert (~ Col A C B).
auto.
eapply notcolnotegal_1.
apply H1.
Qed.
Hint Resolve notcolnotegal_1 notcolnotegal_2 notcolnotegal_3: Geom.
Hint Resolve notparallelnotegal_1 notparallelnotegal_2 : Geom.
(** Some usefull lemmas about ratios of signed distances *)
Proof with Geometry.
intros.
uniformize_dir_seg.
field...
Qed.
Hint Resolve dirseg_1: Geom.
Proof with Geometry.
intros.
uniformize_dir_seg.
rewrite H.
auto.
Qed.
Hint Resolve dirseg_2: Geom.
(* Theorem dirseg_1 : (A,B,C,D:Point) C<>D -> -(A**B/C**D) = B**A /C**D. Proof with Geometry. Intros. Replace A**B with -B**A. Field. Symmetry. Qed.  Theorem dirseg_2 : (A,B,C,D:Point) C<>D -> -(A**B/C**D) = A**B /D**C. Proof with Geometry. Intros. Replace C**D with -D**C. Field. Symmetry. Qed.   Hints Resolve dirseg_1 dirseg_2 : Geom. *)
Proof with Geometry.
intros.
uniformize_dir_seg.
field...
Qed.
Proof with Geometry.
intros...
uniformize_dir_seg.
field...
Qed.
Hint Resolve dirseg_3 dirseg_4: Geom.
Proof with Geometry.
intros.
uniformize_signed_areas.
field...
Qed.
Hint Resolve dirsur_1: Geom.
Proof with Geometry.
intros.
assert (S A B C = S A B D + S A D C + S D B C)...
rewrite H0 in H2.
rewrite H1 in H2.
cases_col A D C...
cases_equality C A...
apply egalcol...
NormalizeRing H2...
assert (C ** B / C ** A = S D C B / S D C A)...
assert (C ** A + A ** B = C ** B)...
rewrite <- H6 in H5...
assert ((C ** A + A ** B) / C ** A = 1 + A ** B / C ** A)...
field...
rewrite H7 in H5.
clear H7 H6.
assert (S D B C = - S D C B)...
rewrite H6 in H2...
assert (S A D C = S D C A)...
rewrite H7 in H2...
IsoleVarRing (S D C B) H2...
rewrite H2 in H5...
assert (S D C A / S D C A = 1)...
field...
rewrite H8 in H5.
clear H6 H7 H8.
IsoleVarRing (A ** B) H5...
assert (A = B)...
intuition...
Qed.
Hint Resolve col_trans_1 : Geom.
Proof with Geometry.
assert ({A : Point &  {B : Point &  {C : Point | ~ Col A B C}}}).
apply A4.
intros.
elim H;intro X;intros.
elim p;intro Y;intros.
elim p0;intro Z;intros.
cases_col A B X.
cases_col A B Y.
cases_col A B Z.
cases_equality Y A.
subst Y.
assert (Col A X Z).
eapply col_trans_1 with (B:=B)...
assert (Col X A Z)...
intuition.
assert (Col A Y Z).
eapply col_trans_1 with (B:=B)...
assert (Col A Y X).
eapply col_trans_1 with (B:=B)...
assert (Col Y X Z).
eapply col_trans_1 with (B:=A)...
assert (Col X Y Z)...
intuition.
exists Z...
exists Y...
exists X...
Qed.
Proof with Geometry.
intros.
assert ({A : Point &  {B : Point &  {C : Point | ~ Col A B C}}}).
apply A4.
DecompEx H A1.
DecompEx p B.
DecompEx p0 C.
cases_equality A B.
subst A.
exists A1.
exists C...
assert  (T:=build_point_not_collinear_1 A B H).
DecompEx T C1.
exists B.
exists C1...
Qed.
Proof with Geometry.
intros.
unfold not in |- *; intro.
assert (Col A O P)...
assert (Col A O B)...
assert (Col A P B)...
eauto with Geom...
Qed.
Hint Resolve col_not_col_1 : Geom.
Proof with try solve [ Geometry | congruence ].
intros...
assert (P ** M / Q ** M = M ** P / M ** Q)...
assert (M ** P / M ** Q = S A M P / S A M Q)...
assert (S A M P = S P A M)...
assert (S A M Q = S Q A M)...
Qed.
Hint Resolve A6_1: Geom.
Proof with try solve [ Geometry | congruence ].
intros...
assert (P ** R / P ** Q = S A P R / S A P Q)...
assert (S A P R = S R A P)...
assert (S A P Q = S Q A P)...
Qed.
Hint Resolve A6_2: Geom.
Proof with Geometry.
intros...
assert (C ** A = - A ** C)...
assert (S P C A = - S P A C)...
assert (C ** B / C ** A = S P C B / S P C A)...
rewrite H3 in H4...
rewrite H2 in H4...
RewriteVar (C ** B) H4...
field...
Qed.
Hint Resolve A6_3: Geom.
Proof with Geometry.
intros...
assert (A ** C / B ** A = S P A C / S P B A)...
assert (A ** C / B ** A = C ** A / A ** B)...
assert (S P C A / S P A B = S P A C / S P B A)...
congruence...
Qed.
Hint Resolve A6_4: Geom.
Proof with Geometry.
intros...
assert (P ** A / O ** A = S P B A / S O B A)...
assert (S P A B = - S P B A)...
assert (S O A B = - S O B A)...
rewrite H3...
rewrite H4...
rewrite H2...
assert (S O B A <> 0)...
field...
Qed.
Hint Resolve A6_5: Geom.
Proof with Geometry.
intros...
assert (S R A B / S Q A B = S R B A / S Q B A)...
rewrite H2...
Qed.
Hint Resolve A6_6: Geom.
Proof with try solve [ Geometry | congruence | field; Geometry ].
intros...
cases_equality C A...
assert (Col A B D)...
rewrite H4...
symmetry  in |- *...
assert (S P C D / S P A B = S P C D / S P C A * (S P C A / S P A B))...
assert (A <> C)...
assert (Col C D A)...
eauto with Geom...
assert (C ** D / C ** A = S P C D / S P C A)...
assert (A ** C / A ** B = S P A C / S P A B)...
assert (C ** A / A ** B = S P C A / S P A B)...
assert (C ** D / C ** A * (C ** A / A ** B) = C ** D / A ** B)...
Qed.
Proof with Geometry.
intros...
unfold parallel in H...
unfold S4 in H...
unfold not in |- *; intro...
assert (S P U Q = 0)...
rewrite H0...
assert (S P Q V = 0)...
rewrite H0...
rewrite H1 in H...
rewrite H2 in H...
Qed.
intros.
cases_col P U Q.
unfold parallel in H.
unfold S4 in H.
rewrite H0 in H.
assert (0 + S P Q V = S P Q V).
ring.
rewrite H1 in H.
right.
unfold Col in |- *.
trivial.
left.
trivial.
Qed.
Proof with try solve [ Geometry | congruence | field; Geometry ].
intros...
assert
(S P A B / S Q A B =
S P A B / S P A M * (S P A M / S Q A M * (S Q A M / S Q A B)))...
assert (A <> B); eauto with Geom...
assert (A <> M); eauto with Geom...
assert (A ** B / A ** M * (P ** M / Q ** M * (A ** M / A ** B)) = P ** M / Q ** M)...
assert (A ** B / A ** M = S P A B / S P A M)...
assert (P ** M / Q ** M = S P A M / S Q A M)...
assert (A ** M / A ** B = S Q A M / S Q A B)...
Qed.
Proof with Geometry.
intros...
cases_equality M A...
rewrite H3...
rewrite H3 in H0...
rewrite H3 in H2...
assert (~ Col Q A M)...
unfold not in |- *; intro...
assert (Col Q M A)...
assert (Col Q M P)...
assert (Col Q A P); eauto with Geom...
assert (Col A M Q)...
assert (Col A M B)...
assert (Col A B Q); eauto with Geom...
cases_equality P M...
rewrite <- H5 in H1...
assert (Col P A B)...
rewrite H6...
assert (P ** M = 0)...
rewrite H7...
field...
cases_equality P Q...
rewrite H6...
field...
assert (~ Col P A M)...
unfold not in |- *; intro...
assert (Col P M A)...
assert (Col P M Q)...
assert (Col P A Q); eauto with Geom...
apply co_side_main...
Qed.
Hint Resolve co_side: Geom.
Proof with Geometry.
intros...
cases_equality A M...
assert (Col A M B)...
assert (Col Q M P)...
rewrite <- H2 in H5...
assert (Col A B P)...
eauto with Geom...
assert (~ Col P A Q \/ ~ Col P Q B)...
apply par_not_all_col...
case H7; intro...
assert (Col P A A)...
rewrite <- H2 in H8...
intuition...
rewrite H2 in H6...
assert (Col P Q B)...
intuition...
Qed.
Proof with Geometry.
intros.
assert (A<>B)
by (intro;subst;auto with Geom).
assert (P<>Q)
by (intro;subst;auto with Geom).
assert (Col A M N)
by (apply (col_trans_1 A B M N);auto).
assert (Col P M N)
by (apply (col_trans_1 P Q M N);auto).
cases_equality M N;auto.
assert (Col M A P)
by (apply (col_trans_1 M N A P); auto with Geom).
assert (Col B M N)
by (apply (col_trans_1 B A M N);auto with Geom).
assert (Col Q M N)
by (apply (col_trans_1 Q P M N);auto with Geom).
assert (Col M Q B)
by (apply (col_trans_1 M N Q B);auto with Geom).
cases_equality P M.
subst.
unfold parallel, S4 in *.
rewrite H12 in H.
basic_simpl.
clear H7 H9 H1 H3.
assert (Col M A Q)
by (apply  (col_trans_1 M N A Q);auto with Geom).
intuition.
assert (Col P A Q)
by (apply (col_trans_1 P M A Q);auto with Geom).
unfold parallel, S4 in *.
rewrite H14 in H.
basic_simpl.
cases_equality Q M.
subst.
clear H1 H11 H12 H14.
assert (Col M P B)
by (apply (col_trans_1 M N P B);auto with Geom).
assert (Col P M B) by auto with Geom.
intuition.
assert (Col Q B P)
by (apply (col_trans_1 Q M B P);auto with Geom).
assert (Col P Q B) by auto with Geom.
intuition.
Qed.
Proof with Geometry.
intros...
assert (P <> Q)...
eapply par_aux_1; apply H...
cases_equality Q M...
assert (Q ** M = 0)...
rewrite H4...
rewrite <- H3 in H0...
assert (Col Q A B)...
unfold parallel in H...
rewrite H5; field...
cases_equality A Q...
assert (A = M)...
apply (inter_unicity A B P Q M H H0 H1 H4)...
rewrite H4...
assert (Q = M)...
congruence...
assert (Q ** M = 0)...
assert (S Q Q B = 0)...
rewrite H7...
rewrite H8...
field...
assert (~ Col Q A B)...
unfold not in |- *; intro...
unfold parallel in H...
unfold S4 in H...
assert (S P A B = S P A Q + S P Q B + S Q A B)...
rewrite H5 in H6...
IsoleVar (S P A Q) H6...
rewrite H6 in H...
assert (S P A B - 0 - S P Q B + S P Q B = S P A B)...
ring...
rewrite H7 in H...
clear H6 H7...
assert (Col A B Q)...
assert (A <> B)...
unfold not in |- *; intro...
assert (S P A B = 0)...
rewrite H7...
assert (Col A M Q); eauto with Geom...
assert (Col Q M P)...
assert (Col Q M A)...
assert (Col Q A P); eauto with Geom...
assert (Col A Q B)...
assert (Col A Q P)...
assert (Col A B P); eauto with Geom...
assert (Col P A B)...
assert (P ** M / Q ** M = S P A B / S Q A B)...
assert (Q ** M / P ** Q * (P ** Q / Q ** M) = 1)...
field...
assert (P ** M / Q ** M - 1 = P ** Q / Q ** M).
replace (P ** Q) with (P ** M - Q ** M).
field...
assert (Q ** M = - M ** Q)...
rewrite H8 in |- *.
ring_simplify...
rewrite <- H8 in H7.
clear H8.
rewrite H6 in H7.
assert (S4 P A Q B = S P A B - S Q A B)...
rewrite H8.
clear H8.
IsoleVar (Q ** M / P ** Q) H7...
rewrite H7.
field...
split...
assert (S4 P A Q B = S P A B - S Q A B)...
unfold parallel in H.
rewrite H9 in H...
assert (S P A B / S Q A B - 1 = (S P A B - S Q A B) / S Q A B).
field...
rewrite H8...
apply nonzerodiv...
assert (S4 P A Q B = S P A B - S Q A B)...
rewrite <- H9...
Qed.
Hint Resolve co_side_bis: Geom.
Proof with Geometry.
intros...
assert (Q ** M / P ** Q = S Q A B / S4 P A Q B)...
assert (P ** Q + Q ** M = P ** M)...
rewrite <- H3...
RewriteVar (Q ** M) H2...
assert (S P A B = S P A Q + S P Q B + S Q A B)...
rewrite H5...
unfold S4 in |- *...
field...
assert (P <> Q)...
eapply par_aux_1; apply H...
Qed.
Hint Resolve co_side_ter: Geom.
Proof with Geometry.
intros...
assert (S R A B = S R A P + S R P B + S P A B)...
assert (P ** R / P ** Q = S R A P / S Q A P)...
RewriteVar (S R A P) H4...
clear H4...
assert (P ** R / P ** Q = S B P R / S B P Q)...
assert (- S B P R = S R P B)...
rewrite <- H6 in H3...
RewriteVar (S B P R) H4...
clear H4 H6...
assert (S R A B = P ** R / P ** Q * (S Q A P - S B P Q) + S P A B)...
rewrite H3...
field...
clear H3...
assert (S A P Q - S B P Q = S4 A P B Q)...
unfold S4 in H3...
assert (S Q A P = S A P Q)...
rewrite <- H6 in H3...
rewrite H3 in H4...
clear H3 H6...
assert (S A B Q = S Q A B)...
rewrite H3 in H4...
clear H3...
assert (S A P B = - S P A B)...
rewrite H3 in H4...
clear H3...
assert
(P ** R / P ** Q * (- S P A B + S Q A B) + S P A B =
P ** R / P ** Q * S Q A B + (1 - P ** R / P ** Q) * S P A B)...
field...
rewrite H3 in H4...
clear H3...
assert (1 - P ** R / P ** Q = R ** Q / P ** Q)...
assert (R ** P + P ** Q = R ** Q)...
rewrite <- H3...
assert (R ** P = - P ** R)...
rewrite H6.
field...
congruence...
Qed.

Theorem l2_9 :
forall A B P Q R : Point,
P <> Q ->
Col R P Q -> S R A B = P ** R / P ** Q * S Q A B + R ** Q / P ** Q * S P A B.