-lemma at_inv_nxn: â\88\80f,i1,i2. @â¦\83i1,fâ¦\84 ≘ i2 → ∀j1,j2. ↑j1 = i1 → ↑j2 = i2 →
- (â\88\83â\88\83g. @â¦\83j1,gâ¦\84 ≘ j2 & ⫯g = f) ∨
- â\88\83â\88\83g. @â¦\83i1,gâ¦\84 ≘ j2 & ↑g = f.
+lemma at_inv_nxn: â\88\80f,i1,i2. @â\9dªi1,fâ\9d« ≘ i2 → ∀j1,j2. ↑j1 = i1 → ↑j2 = i2 →
+ (â\88\83â\88\83g. @â\9dªj1,gâ\9d« ≘ j2 & ⫯g = f) ∨
+ â\88\83â\88\83g. @â\9dªi1,gâ\9d« ≘ j2 & ↑g = f.