[ @sor_pp | @sor_pn | @sor_np | @sor_nn ] /2 width=7 by/
qed-.
+(* Main properties **********************************************************)
+
+axiom monotonic_sle_sor: ∀f1,g1. f1 ⊆ g1 → ∀f2,g2. f2 ⊆ g2 →
+ ∀f. f1 ⋓ f2 ≡ f → ∀g. g1 ⋓ g2 ≡ g → f ⊆ g.
+
+axiom sor_trans1: ∀f0,f3,f4. f0 ⋓ f3 ≡ f4 →
+ ∀f1,f2. f1 ⋓ f2 ≡ f0 →
+ ∀f. f2 ⋓ f3 ≡ f → f1 ⋓ f ≡ f4.
+
+axiom sor_trans2: ∀f1,f0,f4. f1 ⋓ f0 ≡ f4 →
+ ∀f2, f3. f2 ⋓ f3 ≡ f0 →
+ ∀f. f1 ⋓ f2 ≡ f → f ⋓ f3 ≡ f4.
+
(* Properties with tail *****************************************************)
lemma sor_tl: ∀f1,f2,f. f1 ⋓ f2 ≡ f → ⫱f1 ⋓ ⫱f2 ≡ ⫱f.
] -Hf #g #Hg #H destruct //
qed.
+lemma sor_xxn_tl: ∀g1,g2,g. g1 ⋓ g2 ≡ g → ∀f. ⫯f = g →
+ (∃∃f1,f2. f1 ⋓ f2 ≡ f & ⫯f1 = g1 & ⫱g2 = f2) ∨
+ (∃∃f1,f2. f1 ⋓ f2 ≡ f & ⫱g1 = f1 & ⫯f2 = g2).
+#g1 #g2 #g #H #f #H0 elim (sor_inv_xxn … H … H0) -H -H0 *
+/3 width=5 by ex3_2_intro, or_introl, or_intror/
+qed-.
+
(* Properties with iterated tail ********************************************)
lemma sor_tls: ∀f1,f2,f. f1 ⋓ f2 ≡ f →
lemma sor_isid: ∀f1,f2,f. 𝐈⦃f1⦄ → 𝐈⦃f2⦄ → 𝐈⦃f⦄ → f1 ⋓ f2 ≡ f.
/4 width=3 by sor_eq_repl_back2, sor_eq_repl_back1, isid_inv_eq_repl/ qed.
+(* Inversion lemmas with tail ***********************************************)
+
+lemma sor_inv_tl_sn: ∀f1,f2,f. ⫱f1 ⋓ f2 ≡ f → f1 ⋓ ⫯f2 ≡ ⫯f.
+#f1 #f2 #f elim (pn_split f1) *
+#g1 #H destruct /2 width=7 by sor_pn, sor_nn/
+qed-.
+
+lemma sor_inv_tl_dx: ∀f1,f2,f. f1 ⋓ ⫱f2 ≡ f → ⫯f1 ⋓ f2 ≡ ⫯f.
+#f1 #f2 #f elim (pn_split f2) *
+#g2 #H destruct /2 width=7 by sor_np, sor_nn/
+qed-.
+
(* Inversion lemmas with test for identity **********************************)
lemma sor_isid_inv_sn: ∀f1,f2,f. f1 ⋓ f2 ≡ f → 𝐈⦃f1⦄ → f2 ≗ f.
/3 width=5 by sle_push, sle_next, sle_weak/
qed-.
+lemma sor_inv_sle_sn_trans: ∀f1,f2,f. f1 ⋓ f2 ≡ f → ∀g. g ⊆ f1 → g ⊆ f.
+/3 width=4 by sor_inv_sle_sn, sle_trans/ qed-.
+
+lemma sor_inv_sle_dx_trans: ∀f1,f2,f. f1 ⋓ f2 ≡ f → ∀g. g ⊆ f2 → g ⊆ f.
+/3 width=4 by sor_inv_sle_dx, sle_trans/ qed-.
+
+axiom sor_inv_sle: ∀f1,f2,f. f1 ⋓ f2 ≡ f → ∀g. f1 ⊆ g → f2 ⊆ g → f ⊆ g.
+
(* Properties with inclusion ************************************************)
-lemma sor_sle_sn: ∀f1,f2,f. f1 ⋓ f2 ≡ f → ∀g. g ⊆ f1 → g ⊆ f.
-/3 width=4 by sor_inv_sle_sn, sle_trans/ qed.
+corec lemma sor_sle_dx: ∀f1,f2. f1 ⊆ f2 → f1 ⋓ f2 ≡ f2.
+#f1 #f2 * -f1 -f2 /3 width=7 by sor_pp, sor_nn, sor_pn/
+qed.
-lemma sor_sle_dx: ∀f1,f2,f. f1 ⋓ f2 ≡ f → ∀g. g ⊆ f2 → g ⊆ f.
-/3 width=4 by sor_inv_sle_dx, sle_trans/ qed.
+corec lemma sor_sle_sn: ∀f1,f2. f1 ⊆ f2 → f2 ⋓ f1 ≡ f2.
+#f1 #f2 * -f1 -f2 /3 width=7 by sor_pp, sor_nn, sor_np/
+qed.