From: Ferruccio Guidi Date: Sun, 29 May 2016 18:13:10 +0000 (+0000) Subject: more results on sor ... X-Git-Tag: make_still_working~574 X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=commitdiff_plain;h=f215e6c18fbd22a049e6d34cf3bb52b0cabc4d58;p=helm.git more results on sor ... --- diff --git a/matita/matita/contribs/lambdadelta/ground_2/relocation/rtmap_after.ma b/matita/matita/contribs/lambdadelta/ground_2/relocation/rtmap_after.ma index a00a10d16..fef085189 100644 --- a/matita/matita/contribs/lambdadelta/ground_2/relocation/rtmap_after.ma +++ b/matita/matita/contribs/lambdadelta/ground_2/relocation/rtmap_after.ma @@ -13,6 +13,7 @@ (**************************************************************************) include "ground_2/notation/relations/rafter_3.ma". +include "ground_2/relocation/rtmap_sor.ma". include "ground_2/relocation/rtmap_istot.ma". (* RELOCATION MAP ***********************************************************) @@ -161,7 +162,7 @@ qed-. (* Basic properties *********************************************************) -corec lemma after_eq_repl_back_2: ∀f1,f. eq_repl_back (λf2. f2 ⊚ f1 ≡ f). +corec lemma after_eq_repl_back2: ∀f1,f. eq_repl_back (λf2. f2 ⊚ f1 ≡ f). #f1 #f #f2 * -f2 -f1 -f #f21 #f1 #f #g21 [1,2: #g1 ] #g #Hf #H21 [1,2: #H1 ] #H #g22 #H0 [ cases (eq_inv_px … H0 … H21) -g21 /3 width=7 by after_refl/ @@ -170,11 +171,11 @@ corec lemma after_eq_repl_back_2: ∀f1,f. eq_repl_back (λf2. f2 ⊚ f1 ≡ f). ] qed-. -lemma after_eq_repl_fwd_2: ∀f1,f. eq_repl_fwd (λf2. f2 ⊚ f1 ≡ f). -#f1 #f @eq_repl_sym /2 width=3 by after_eq_repl_back_2/ +lemma after_eq_repl_fwd2: ∀f1,f. eq_repl_fwd (λf2. f2 ⊚ f1 ≡ f). +#f1 #f @eq_repl_sym /2 width=3 by after_eq_repl_back2/ qed-. -corec lemma after_eq_repl_back_1: ∀f2,f. eq_repl_back (λf1. f2 ⊚ f1 ≡ f). +corec lemma after_eq_repl_back1: ∀f2,f. eq_repl_back (λf1. f2 ⊚ f1 ≡ f). #f2 #f #f1 * -f2 -f1 -f #f2 #f11 #f #g2 [1,2: #g11 ] #g #Hf #H2 [1,2: #H11 ] #H #g2 #H0 [ cases (eq_inv_px … H0 … H11) -g11 /3 width=7 by after_refl/ @@ -183,21 +184,21 @@ corec lemma after_eq_repl_back_1: ∀f2,f. eq_repl_back (λf1. f2 ⊚ f1 ≡ f). ] qed-. -lemma after_eq_repl_fwd_1: ∀f2,f. eq_repl_fwd (λf1. f2 ⊚ f1 ≡ f). -#f2 #f @eq_repl_sym /2 width=3 by after_eq_repl_back_1/ +lemma after_eq_repl_fwd1: ∀f2,f. eq_repl_fwd (λf1. f2 ⊚ f1 ≡ f). +#f2 #f @eq_repl_sym /2 width=3 by after_eq_repl_back1/ qed-. -corec lemma after_eq_repl_back_0: ∀f1,f2. eq_repl_back (λf. f2 ⊚ f1 ≡ f). +corec lemma after_eq_repl_back0: ∀f1,f2. eq_repl_back (λf. f2 ⊚ f1 ≡ f). #f2 #f1 #f * -f2 -f1 -f #f2 #f1 #f01 #g2 [1,2: #g1 ] #g01 #Hf01 #H2 [1,2: #H1 ] #H01 #g02 #H0 [ cases (eq_inv_px … H0 … H01) -g01 /3 width=7 by after_refl/ | cases (eq_inv_nx … H0 … H01) -g01 /3 width=7 by after_push/ -| cases (eq_inv_nx … H0 … H01) -g01 /3 width=5 by after_next/ +| cases (eq_inv_nx … H0 … H01) -g01 /3 width=5 by after_next/ ] qed-. -lemma after_eq_repl_fwd_0: ∀f2,f1. eq_repl_fwd (λf. f2 ⊚ f1 ≡ f). -#f2 #f1 @eq_repl_sym /2 width=3 by after_eq_repl_back_0/ +lemma after_eq_repl_fwd0: ∀f2,f1. eq_repl_fwd (λf. f2 ⊚ f1 ≡ f). +#f2 #f1 @eq_repl_sym /2 width=3 by after_eq_repl_back0/ qed-. (* Main properties **********************************************************) @@ -263,7 +264,7 @@ qed-. lemma after_mono_eq: ∀f1,f2,f. f1 ⊚ f2 ≡ f → ∀g1,g2,g. g1 ⊚ g2 ≡ g → f1 ≗ g1 → f2 ≗ g2 → f ≗ g. -/4 width=4 by after_mono, after_eq_repl_back_1, after_eq_repl_back_2/ qed-. +/4 width=4 by after_mono, after_eq_repl_back1, after_eq_repl_back2/ qed-. (* Properties on tls ********************************************************) @@ -274,27 +275,27 @@ lemma after_tls: ∀n,f1,f2,f. @⦃0, f1⦄ ≡ n → #g1 #Hg1 #H1 cases (after_inv_nxx … Hf … H1) -Hf /2 width=1 by/ qed. -(* Inversion lemmas on isid *************************************************) +(* Properties on isid *******************************************************) -corec lemma isid_after_sn: ∀f1. 𝐈⦃f1⦄ → ∀f2. f1 ⊚ f2 ≡ f2. +corec lemma after_isid_sn: ∀f1. 𝐈⦃f1⦄ → ∀f2. f1 ⊚ f2 ≡ f2. #f1 * -f1 #f1 #g1 #Hf1 #H1 #f2 cases (pn_split f2) * #g2 #H2 /3 width=7 by after_push, after_refl/ -qed-. +qed. -corec lemma isid_after_dx: ∀f2. 𝐈⦃f2⦄ → ∀f1. f1 ⊚ f2 ≡ f1. +corec lemma after_isid_dx: ∀f2. 𝐈⦃f2⦄ → ∀f1. f1 ⊚ f2 ≡ f1. #f2 * -f2 #f2 #g2 #Hf2 #H2 #f1 cases (pn_split f1) * #g1 #H1 [ /3 width=7 by after_refl/ | @(after_next … H1 H1) /3 width=3 by isid_push/ ] -qed-. +qed. -lemma after_isid_inv_sn: ∀f1,f2,f. f1 ⊚ f2 ≡ f → 𝐈⦃f1⦄ → f2 ≗ f. -/3 width=6 by isid_after_sn, after_mono/ -qed-. +(* Inversion lemmas on isid *************************************************) -lemma after_isid_inv_dx: ∀f1,f2,f. f1 ⊚ f2 ≡ f → 𝐈⦃f2⦄ → f1 ≗ f. -/3 width=6 by isid_after_dx, after_mono/ -qed-. +lemma after_isid_inv_sn: ∀f1,f2,f. f1 ⊚ f2 ≡ f → 𝐈⦃f1⦄ → f2 ≗ f. +/3 width=6 by after_isid_sn, after_mono/ qed-. + +lemma after_isid_inv_dx: ∀f1,f2,f. f1 ⊚ f2 ≡ f → 𝐈⦃f2⦄ → f1 ≗ f. +/3 width=6 by after_isid_dx, after_mono/ qed-. corec lemma after_fwd_isid1: ∀f1,f2,f. f1 ⊚ f2 ≡ f → 𝐈⦃f⦄ → 𝐈⦃f1⦄. #f1 #f2 #f * -f1 -f2 -f @@ -317,14 +318,14 @@ lemma after_inv_isid3: ∀f1,f2,f. f1 ⊚ f2 ≡ f → 𝐈⦃f⦄ → 𝐈⦃f1 lemma after_isid_isuni: ∀f1,f2. 𝐈⦃f2⦄ → 𝐔⦃f1⦄ → f1 ⊚ ⫯f2 ≡ ⫯f1. #f1 #f2 #Hf2 #H elim H -H -/5 width=7 by isid_after_dx, after_eq_repl_back_2, after_next, after_push, eq_push_inv_isid/ +/5 width=7 by after_isid_dx, after_eq_repl_back2, after_next, after_push, eq_push_inv_isid/ qed. lemma after_uni_next2: ∀f2. 𝐔⦃f2⦄ → ∀f1,f. ⫯f2 ⊚ f1 ≡ f → f2 ⊚ ⫯f1 ≡ f. #f2 #H elim H -f2 [ #f2 #Hf2 #f1 #f #Hf elim (after_inv_nxx … Hf) -Hf [2,3: // ] #g #Hg #H0 destruct - /4 width=7 by after_isid_inv_sn, isid_after_sn, after_eq_repl_back_0, eq_next/ + /4 width=7 by after_isid_inv_sn, after_isid_sn, after_eq_repl_back0, eq_next/ | #f2 #_ #g2 #H2 #IH #f1 #f #Hf elim (after_inv_nxx … Hf) -Hf [2,3: // ] #g #Hg #H0 destruct /3 width=5 by after_next/ @@ -335,9 +336,35 @@ qed. lemma after_uni: ∀n1,n2. 𝐔❴n1❵ ⊚ 𝐔❴n2❵ ≡ 𝐔❴n1+n2❵. @nat_elim2 -/4 width=5 by after_uni_next2, isid_after_sn, isid_after_dx, after_next/ +/4 width=5 by after_uni_next2, after_isid_sn, after_isid_dx, after_next/ qed. +(* Inversion lemmas on sor **************************************************) + +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. +(* +lemma after_inv_sor: ∀f. 𝐅⦃f⦄ → ∀f2,f1. f2 ⊚ f1 ≡ f → ∀fa,fb. fa ⋓ fb ≡ f → + ∃∃f1a,f1b. f2 ⊚ f1a ≡ fa & f2 ⊚ f1b ≡ fb & f1a ⋓ f1b ≡ f1. +@isfin_ind +[ #f #Hf #f2 #f1 #H1f #fa #fb #H2f + elim (after_inv_isid3 … H1f) -H1f // + elim (sor_inv_isid3 … H2f) -H2f // + /3 width=5 by ex3_2_intro, after_isid_sn, sor_isid/ +| #f #_ #IH #f2 #f1 #H1 #fa #fb #H2 + elim (after_inv_xxp … H1) -H1 [ |*: // ] #g2 #g1 #H1f + elim (sor_inv_xxp … H2) -H2 [ |*: // ] #ga #gb #H2f + elim (IH … H1f … H2f) -f /3 width=11 by sor_pp, after_refl, ex3_2_intro/ +| #f #_ #IH #f2 #f1 #H1 #fa #fb #H2 + elim (sor_inv_xxn … H2) -H2 [1,3,4: * |*: // ] #ga #gb #H2f + elim (after_inv_xxn … H1) -H1 [1,3,5,7,9,11: * |*: // ] #g2 [1,3,5: #g1 ] #H1f + elim (IH … H1f … H2f) -f + /3 width=11 by sor_np, sor_pn, sor_nn, after_refl, after_push, after_next, ex3_2_intro/ + #x1a #x1b #H39 #H40 #H41 #H42 #H43 #H44 + [ @ex3_2_intro + [3: /2 width=7 by after_next/ | skip + |5: @H41 | skip +*) (* Forward lemmas on at *****************************************************) lemma after_at_fwd: ∀i,i1,f. @⦃i1, f⦄ ≡ i → ∀f2,f1. f2 ⊚ f1 ≡ f → @@ -407,7 +434,7 @@ lemma after_uni_dx: ∀i2,i1,f2. @⦃i1, f2⦄ ≡ i2 → [ #i1 #f2 #Hf2 #f #Hf elim (at_inv_xxp … Hf2) -Hf2 // #g2 #H1 #H2 destruct lapply (after_isid_inv_dx … Hf ?) -Hf - /3 width=3 by isid_after_sn, after_eq_repl_back_0/ + /3 width=3 by after_isid_sn, after_eq_repl_back0/ | #i2 #IH #i1 #f2 #Hf2 #f #Hf elim (at_inv_xxn … Hf2) -Hf2 [1,3: * |*: // ] [ #g2 #j1 #Hg2 #H1 #H2 destruct @@ -426,7 +453,7 @@ lemma after_uni_sn: ∀i2,i1,f2. @⦃i1, f2⦄ ≡ i2 → [ #i1 #f2 #Hf2 #f #Hf elim (at_inv_xxp … Hf2) -Hf2 // #g2 #H1 #H2 destruct lapply (after_isid_inv_sn … Hf ?) -Hf - /3 width=3 by isid_after_dx, after_eq_repl_back_0/ + /3 width=3 by after_isid_dx, after_eq_repl_back0/ | #i2 #IH #i1 #f2 #Hf2 #f #Hf elim (after_inv_nxx … Hf) -Hf [2,3: // ] #g #Hg #H destruct elim (at_inv_xxn … Hf2) -Hf2 [1,3: * |*: // ] @@ -443,7 +470,7 @@ lemma after_uni_succ_dx: ∀i2,i1,f2. @⦃i1, f2⦄ ≡ i2 → elim (at_inv_xxp … Hf2) -Hf2 // #g2 #H1 #H2 destruct elim (after_inv_pnx … Hf) -Hf [ |*: // ] #g #Hg #H lapply (after_isid_inv_dx … Hg ?) -Hg - /4 width=5 by isid_after_sn, after_eq_repl_back_0, after_next/ + /4 width=5 by after_isid_sn, after_eq_repl_back0, after_next/ | #i2 #IH #i1 #f2 #Hf2 #f #Hf elim (at_inv_xxn … Hf2) -Hf2 [1,3: * |*: // ] [ #g2 #j1 #Hg2 #H1 #H2 destruct @@ -463,7 +490,7 @@ lemma after_uni_succ_sn: ∀i2,i1,f2. @⦃i1, f2⦄ ≡ i2 → elim (at_inv_xxp … Hf2) -Hf2 // #g2 #H1 #H2 destruct elim (after_inv_nxx … Hf) -Hf [ |*: // ] #g #Hg #H destruct lapply (after_isid_inv_sn … Hg ?) -Hg - /4 width=7 by isid_after_dx, after_eq_repl_back_0, after_push/ + /4 width=7 by after_isid_dx, after_eq_repl_back0, after_push/ | #i2 #IH #i1 #f2 #Hf2 #f #Hf elim (after_inv_nxx … Hf) -Hf [2,3: // ] #g #Hg #H destruct elim (at_inv_xxn … Hf2) -Hf2 [1,3: * |*: // ] diff --git a/matita/matita/contribs/lambdadelta/ground_2/relocation/rtmap_sor.ma b/matita/matita/contribs/lambdadelta/ground_2/relocation/rtmap_sor.ma index e76c1ca3c..8f38b8062 100644 --- a/matita/matita/contribs/lambdadelta/ground_2/relocation/rtmap_sor.ma +++ b/matita/matita/contribs/lambdadelta/ground_2/relocation/rtmap_sor.ma @@ -72,6 +72,141 @@ try elim (discr_push_next … Hx2) try elim (discr_next_push … Hx2) /2 width=3 by ex2_intro/ qed-. +(* Advanced inversion lemmas ************************************************) + +lemma sor_inv_ppn: ∀g1,g2,g. g1 ⋓ g2 ≡ g → + ∀f1,f2,f. ↑f1 = g1 → ↑f2 = g2 → ⫯f = g → ⊥. +#g1 #g2 #g #H #f1 #f2 #f #H1 #H2 #H0 +elim (sor_inv_ppx … H … H1 H2) -g1 -g2 #x #_ #H destruct +/2 width=3 by discr_push_next/ +qed-. + +lemma sor_inv_nxp: ∀g1,g2,g. g1 ⋓ g2 ≡ g → + ∀f1,f. ⫯f1 = g1 → ↑f = g → ⊥. +#g1 #g2 #g #H #f1 #f #H1 #H0 +elim (pn_split g2) * #f2 #H2 +[ elim (sor_inv_npx … H … H1 H2) +| elim (sor_inv_nnx … H … H1 H2) +] -g1 -g2 #x #_ #H destruct +/2 width=3 by discr_next_push/ +qed-. + +lemma sor_inv_xnp: ∀g1,g2,g. g1 ⋓ g2 ≡ g → + ∀f2,f. ⫯f2 = g2 → ↑f = g → ⊥. +#g1 #g2 #g #H #f2 #f #H2 #H0 +elim (pn_split g1) * #f1 #H1 +[ elim (sor_inv_pnx … H … H1 H2) +| elim (sor_inv_nnx … H … H1 H2) +] -g1 -g2 #x #_ #H destruct +/2 width=3 by discr_next_push/ +qed-. + +lemma sor_inv_ppp: ∀g1,g2,g. g1 ⋓ g2 ≡ g → + ∀f1,f2,f. ↑f1 = g1 → ↑f2 = g2 → ↑f = g → f1 ⋓ f2 ≡ f. +#g1 #g2 #g #H #f1 #f2 #f #H1 #H2 #H0 +elim (sor_inv_ppx … H … H1 H2) -g1 -g2 #x #Hx #H destruct +<(injective_push … H) -f // +qed-. + +lemma sor_inv_npn: ∀g1,g2,g. g1 ⋓ g2 ≡ g → + ∀f1,f2,f. ⫯f1 = g1 → ↑f2 = g2 → ⫯f = g → f1 ⋓ f2 ≡ f. +#g1 #g2 #g #H #f1 #f2 #f #H1 #H2 #H0 +elim (sor_inv_npx … H … H1 H2) -g1 -g2 #x #Hx #H destruct +<(injective_next … H) -f // +qed-. + +lemma sor_inv_pnn: ∀g1,g2,g. g1 ⋓ g2 ≡ g → + ∀f1,f2,f. ↑f1 = g1 → ⫯f2 = g2 → ⫯f = g → f1 ⋓ f2 ≡ f. +#g1 #g2 #g #H #f1 #f2 #f #H1 #H2 #H0 +elim (sor_inv_pnx … H … H1 H2) -g1 -g2 #x #Hx #H destruct +<(injective_next … H) -f // +qed-. + +lemma sor_inv_nnn: ∀g1,g2,g. g1 ⋓ g2 ≡ g → + ∀f1,f2,f. ⫯f1 = g1 → ⫯f2 = g2 → ⫯f = g → f1 ⋓ f2 ≡ f. +#g1 #g2 #g #H #f1 #f2 #f #H1 #H2 #H0 +elim (sor_inv_nnx … H … H1 H2) -g1 -g2 #x #Hx #H destruct +<(injective_next … H) -f // +qed-. + +lemma sor_inv_pxp: ∀g1,g2,g. g1 ⋓ g2 ≡ g → + ∀f1,f. ↑f1 = g1 → ↑f = g → + ∃∃f2. f1 ⋓ f2 ≡ f & ↑f2 = g2. +#g1 #g2 #g #H #f1 #f #H1 #H0 +elim (pn_split g2) * #f2 #H2 +[ /3 width=7 by sor_inv_ppp, ex2_intro/ +| elim (sor_inv_xnp … H … H2 H0) +] +qed-. + +lemma sor_inv_xpp: ∀g1,g2,g. g1 ⋓ g2 ≡ g → + ∀f2,f. ↑f2 = g2 → ↑f = g → + ∃∃f1. f1 ⋓ f2 ≡ f & ↑f1 = g1. +#g1 #g2 #g #H #f2 #f #H2 #H0 +elim (pn_split g1) * #f1 #H1 +[ /3 width=7 by sor_inv_ppp, ex2_intro/ +| elim (sor_inv_nxp … H … H1 H0) +] +qed-. + +lemma sor_inv_pxn: ∀g1,g2,g. g1 ⋓ g2 ≡ g → + ∀f1,f. ↑f1 = g1 → ⫯f = g → + ∃∃f2. f1 ⋓ f2 ≡ f & ⫯f2 = g2. +#g1 #g2 #g #H #f1 #f #H1 #H0 +elim (pn_split g2) * #f2 #H2 +[ elim (sor_inv_ppn … H … H1 H2 H0) +| /3 width=7 by sor_inv_pnn, ex2_intro/ +] +qed-. + +lemma sor_inv_xpn: ∀g1,g2,g. g1 ⋓ g2 ≡ g → + ∀f2,f. ↑f2 = g2 → ⫯f = g → + ∃∃f1. f1 ⋓ f2 ≡ f & ⫯f1 = g1. +#g1 #g2 #g #H #f2 #f #H2 #H0 +elim (pn_split g1) * #f1 #H1 +[ elim (sor_inv_ppn … H … H1 H2 H0) +| /3 width=7 by sor_inv_npn, ex2_intro/ +] +qed-. + +lemma sor_inv_xxp: ∀g1,g2,g. g1 ⋓ g2 ≡ g → ∀f. ↑f = g → + ∃∃f1,f2. f1 ⋓ f2 ≡ f & ↑f1 = g1 & ↑f2 = g2. +#g1 #g2 #g #H #f #H0 +elim (pn_split g1) * #f1 #H1 +[ elim (sor_inv_pxp … H … H1 H0) -g /2 width=5 by ex3_2_intro/ +| elim (sor_inv_nxp … H … H1 H0) +] +qed-. + +lemma sor_inv_nxn: ∀g1,g2,g. g1 ⋓ g2 ≡ g → + ∀f1,f. ⫯f1 = g1 → ⫯f = g → + (∃∃f2. f1 ⋓ f2 ≡ f & ↑f2 = g2) ∨ + ∃∃f2. f1 ⋓ f2 ≡ f & ⫯f2 = g2. +#g1 #g2 elim (pn_split g2) * +/4 width=7 by sor_inv_npn, sor_inv_nnn, ex2_intro, or_intror, or_introl/ +qed-. + +lemma sor_inv_xnn: ∀g1,g2,g. g1 ⋓ g2 ≡ g → + ∀f2,f. ⫯f2 = g2 → ⫯f = g → + (∃∃f1. f1 ⋓ f2 ≡ f & ↑f1 = g1) ∨ + ∃∃f1. f1 ⋓ f2 ≡ f & ⫯f1 = g1. +#g1 elim (pn_split g1) * +/4 width=7 by sor_inv_pnn, sor_inv_nnn, ex2_intro, or_intror, or_introl/ +qed-. + +lemma sor_inv_xxn: ∀g1,g2,g. g1 ⋓ g2 ≡ g → ∀f. ⫯f = g → + ∨∨ ∃∃f1,f2. f1 ⋓ f2 ≡ f & ⫯f1 = g1 & ↑f2 = g2 + | ∃∃f1,f2. f1 ⋓ f2 ≡ f & ↑f1 = g1 & ⫯f2 = g2 + | ∃∃f1,f2. f1 ⋓ f2 ≡ f & ⫯f1 = g1 & ⫯f2 = g2. +#g1 #g2 #g #H #f #H0 +elim (pn_split g1) * #f1 #H1 +[ elim (sor_inv_pxn … H … H1 H0) -g + /3 width=5 by or3_intro1, ex3_2_intro/ +| elim (sor_inv_nxn … H … H1 H0) -g * + /3 width=5 by or3_intro0, or3_intro2, ex3_2_intro/ +] +qed-. + (* Main inversion lemmas ****************************************************) corec theorem sor_mono: ∀f1,f2,x,y. f1 ⋓ f2 ≡ x → f1 ⋓ f2 ≡ y → x ≗ y. @@ -131,7 +266,7 @@ corec lemma sor_sym: ∀f1,f2,f. f1 ⋓ f2 ≡ f → f2 ⋓ f1 ≡ f. [ @sor_pp | @sor_pn | @sor_np | @sor_nn ] /2 width=7 by/ qed-. -(* Properies on identity ****************************************************) +(* Properies on test for identity *******************************************) corec lemma sor_isid_sn: ∀f1. 𝐈⦃f1⦄ → ∀f2. f1 ⋓ f2 ≡ f2. #f1 * -f1 @@ -145,6 +280,33 @@ corec lemma sor_isid_dx: ∀f2. 𝐈⦃f2⦄ → ∀f1. f1 ⋓ f2 ≡ f1. /3 width=7 by sor_pp, sor_np/ qed. +(* Inversion lemmas on test for identity ************************************) + +lemma sor_isid_inv_sn: ∀f1,f2,f. f1 ⋓ f2 ≡ f → 𝐈⦃f1⦄ → f2 ≗ f. +/3 width=4 by sor_isid_sn, sor_mono/ +qed-. + +lemma sor_isid_inv_dx: ∀f1,f2,f. f1 ⋓ f2 ≡ f → 𝐈⦃f2⦄ → f1 ≗ f. +/3 width=4 by sor_isid_dx, sor_mono/ +qed-. + +corec lemma sor_fwd_isid1: ∀f1,f2,f. f1 ⋓ f2 ≡ f → 𝐈⦃f⦄ → 𝐈⦃f1⦄. +#f1 #f2 #f * -f1 -f2 -f +#f1 #f2 #f #g1 #g2 #g #Hf #H1 #H2 #H #Hg +[ /4 width=6 by isid_inv_push, isid_push/ ] +cases (isid_inv_next … Hg … H) +qed-. + +corec lemma sor_fwd_isid2: ∀f1,f2,f. f1 ⋓ f2 ≡ f → 𝐈⦃f⦄ → 𝐈⦃f2⦄. +#f1 #f2 #f * -f1 -f2 -f +#f1 #f2 #f #g1 #g2 #g #Hf #H1 #H2 #H #Hg +[ /4 width=6 by isid_inv_push, isid_push/ ] +cases (isid_inv_next … Hg … H) +qed-. + +lemma sor_inv_isid3: ∀f1,f2,f. f1 ⋓ f2 ≡ f → 𝐈⦃f⦄ → 𝐈⦃f1⦄ ∧ 𝐈⦃f2⦄. +/3 width=4 by sor_fwd_isid2, sor_fwd_isid1, conj/ qed-. + (* Properties on finite colength assignment *********************************) lemma sor_fcla_ex: ∀f1,n1. 𝐂⦃f1⦄ ≡ n1 → ∀f2,n2. 𝐂⦃f2⦄ ≡ n2 →