(*** sor_fcla_ex *)
lemma pr_sor_fcla_bi:
- â\88\80f1,n1. ð\9d\90\82â\9dªf1â\9d« â\89\98 n1 â\86\92 â\88\80f2,n2. ð\9d\90\82â\9dªf2â\9d« ≘ n2 →
- â\88\83â\88\83f,n. f1 â\8b\93 f2 â\89\98 f & ð\9d\90\82â\9dªfâ\9d« ≘ n & (n1 ∨ n2) ≤ n & n ≤ n1 + n2.
+ â\88\80f1,n1. ð\9d\90\82â\9d¨f1â\9d© â\89\98 n1 â\86\92 â\88\80f2,n2. ð\9d\90\82â\9d¨f2â\9d© ≘ n2 →
+ â\88\83â\88\83f,n. f1 â\8b\93 f2 â\89\98 f & ð\9d\90\82â\9d¨fâ\9d© ≘ n & (n1 ∨ n2) ≤ n & n ≤ n1 + n2.
#f1 #n1 #Hf1 elim Hf1 -f1 -n1 /3 width=6 by pr_sor_isi_sn, ex4_2_intro/
#f1 #n1 #Hf1 #IH #f2 #n2 * -f2 -n2 /3 width=6 by pr_fcla_push, pr_fcla_next, ex4_2_intro, pr_sor_isi_dx/
#f2 #n2 #Hf2 elim (IH … Hf2) -IH -Hf2 -Hf1 [2,4: #f #n <nplus_succ_dx ] (* * full auto fails *)
(*** sor_fcla *)
lemma pr_sor_inv_fcla_bi:
- â\88\80f1,n1. ð\9d\90\82â\9dªf1â\9d« â\89\98 n1 â\86\92 â\88\80f2,n2. ð\9d\90\82â\9dªf2â\9d« ≘ n2 → ∀f. f1 ⋓ f2 ≘ f →
- â\88\83â\88\83n. ð\9d\90\82â\9dªfâ\9d« ≘ n & (n1 ∨ n2) ≤ n & n ≤ n1 + n2.
+ â\88\80f1,n1. ð\9d\90\82â\9d¨f1â\9d© â\89\98 n1 â\86\92 â\88\80f2,n2. ð\9d\90\82â\9d¨f2â\9d© ≘ n2 → ∀f. f1 ⋓ f2 ≘ f →
+ â\88\83â\88\83n. ð\9d\90\82â\9d¨fâ\9d© ≘ n & (n1 ∨ n2) ≤ n & n ≤ n1 + n2.
#f1 #n1 #Hf1 #f2 #n2 #Hf2 #f #Hf elim (pr_sor_fcla_bi … Hf1 … Hf2) -Hf1 -Hf2
/4 width=6 by pr_sor_mono, pr_fcla_eq_repl_back, ex3_intro/
qed-.
(*** sor_fwd_fcla_sn_ex *)
lemma pr_sor_des_fcla_sn:
- â\88\80f,n. ð\9d\90\82â\9dªfâ\9d« ≘ n → ∀f1,f2. f1 ⋓ f2 ≘ f →
- â\88\83â\88\83n1. ð\9d\90\82â\9dªf1â\9d« ≘ n1 & n1 ≤ n.
+ â\88\80f,n. ð\9d\90\82â\9d¨fâ\9d© ≘ n → ∀f1,f2. f1 ⋓ f2 ≘ f →
+ â\88\83â\88\83n1. ð\9d\90\82â\9d¨f1â\9d© ≘ n1 & n1 ≤ n.
#f #n #H elim H -f -n
[ /4 width=4 by pr_sor_des_isi_sn, pr_fcla_isi, ex2_intro/
| #f #n #_ #IH #f1 #f2 #H
(*** sor_fwd_fcla_dx_ex *)
lemma pr_sor_des_fcla_dx:
- â\88\80f,n. ð\9d\90\82â\9dªfâ\9d« ≘ n → ∀f1,f2. f1 ⋓ f2 ≘ f →
- â\88\83â\88\83n2. ð\9d\90\82â\9dªf2â\9d« ≘ n2 & n2 ≤ n.
+ â\88\80f,n. ð\9d\90\82â\9d¨fâ\9d© ≘ n → ∀f1,f2. f1 ⋓ f2 ≘ f →
+ â\88\83â\88\83n2. ð\9d\90\82â\9d¨f2â\9d© ≘ n2 & n2 ≤ n.
/3 width=4 by pr_sor_des_fcla_sn, pr_sor_comm/ qed-.