lemma ifr_unwind_bi (f) (p) (q) (t1) (t2):
t1 ϵ 𝐓 → t1⋔(p◖𝗦) ⧸≬ 𝐈 →
- t1 â\9e¡ð\9d\90\9f[p,q] t2 â\86\92 â\96¼[f]t1 â\9e¡𝐟[⊗p,⊗q] ▼[f]t2.
+ t1 â\9e¡ð\9d\90¢ð\9d\90\9f[p,q] t2 â\86\92 â\96¼[f]t1 â\9e¡ð\9d\90¢𝐟[⊗p,⊗q] ▼[f]t2.
#f #p #q #t1 #t2 #H1t1 #H2t1
* #n * #H1n #Ht1 #Ht2
@(ex_intro … (↑♭q)) @and3_intro