| Step | Hyp | Ref
 | Expression | 
| 1 |   | f1of 5504 | 
. . . . . . . 8
⊢ (𝐻:𝐴–1-1-onto→𝐵 → 𝐻:𝐴⟶𝐵) | 
| 2 |   | ffvelcdm 5695 | 
. . . . . . . . . 10
⊢ ((𝐻:𝐴⟶𝐵 ∧ 𝑥 ∈ 𝐴) → (𝐻‘𝑥) ∈ 𝐵) | 
| 3 | 2 | adantrr 479 | 
. . . . . . . . 9
⊢ ((𝐻:𝐴⟶𝐵 ∧ (𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐴)) → (𝐻‘𝑥) ∈ 𝐵) | 
| 4 |   | ffvelcdm 5695 | 
. . . . . . . . . 10
⊢ ((𝐻:𝐴⟶𝐵 ∧ 𝑦 ∈ 𝐴) → (𝐻‘𝑦) ∈ 𝐵) | 
| 5 | 4 | adantrl 478 | 
. . . . . . . . 9
⊢ ((𝐻:𝐴⟶𝐵 ∧ (𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐴)) → (𝐻‘𝑦) ∈ 𝐵) | 
| 6 |   | brinxp 4731 | 
. . . . . . . . 9
⊢ (((𝐻‘𝑥) ∈ 𝐵 ∧ (𝐻‘𝑦) ∈ 𝐵) → ((𝐻‘𝑥)𝑆(𝐻‘𝑦) ↔ (𝐻‘𝑥)(𝑆 ∩ (𝐵 × 𝐵))(𝐻‘𝑦))) | 
| 7 | 3, 5, 6 | syl2anc 411 | 
. . . . . . . 8
⊢ ((𝐻:𝐴⟶𝐵 ∧ (𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐴)) → ((𝐻‘𝑥)𝑆(𝐻‘𝑦) ↔ (𝐻‘𝑥)(𝑆 ∩ (𝐵 × 𝐵))(𝐻‘𝑦))) | 
| 8 | 1, 7 | sylan 283 | 
. . . . . . 7
⊢ ((𝐻:𝐴–1-1-onto→𝐵 ∧ (𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐴)) → ((𝐻‘𝑥)𝑆(𝐻‘𝑦) ↔ (𝐻‘𝑥)(𝑆 ∩ (𝐵 × 𝐵))(𝐻‘𝑦))) | 
| 9 | 8 | anassrs 400 | 
. . . . . 6
⊢ (((𝐻:𝐴–1-1-onto→𝐵 ∧ 𝑥 ∈ 𝐴) ∧ 𝑦 ∈ 𝐴) → ((𝐻‘𝑥)𝑆(𝐻‘𝑦) ↔ (𝐻‘𝑥)(𝑆 ∩ (𝐵 × 𝐵))(𝐻‘𝑦))) | 
| 10 | 9 | bibi2d 232 | 
. . . . 5
⊢ (((𝐻:𝐴–1-1-onto→𝐵 ∧ 𝑥 ∈ 𝐴) ∧ 𝑦 ∈ 𝐴) → ((𝑥𝑅𝑦 ↔ (𝐻‘𝑥)𝑆(𝐻‘𝑦)) ↔ (𝑥𝑅𝑦 ↔ (𝐻‘𝑥)(𝑆 ∩ (𝐵 × 𝐵))(𝐻‘𝑦)))) | 
| 11 | 10 | ralbidva 2493 | 
. . . 4
⊢ ((𝐻:𝐴–1-1-onto→𝐵 ∧ 𝑥 ∈ 𝐴) → (∀𝑦 ∈ 𝐴 (𝑥𝑅𝑦 ↔ (𝐻‘𝑥)𝑆(𝐻‘𝑦)) ↔ ∀𝑦 ∈ 𝐴 (𝑥𝑅𝑦 ↔ (𝐻‘𝑥)(𝑆 ∩ (𝐵 × 𝐵))(𝐻‘𝑦)))) | 
| 12 | 11 | ralbidva 2493 | 
. . 3
⊢ (𝐻:𝐴–1-1-onto→𝐵 → (∀𝑥 ∈ 𝐴 ∀𝑦 ∈ 𝐴 (𝑥𝑅𝑦 ↔ (𝐻‘𝑥)𝑆(𝐻‘𝑦)) ↔ ∀𝑥 ∈ 𝐴 ∀𝑦 ∈ 𝐴 (𝑥𝑅𝑦 ↔ (𝐻‘𝑥)(𝑆 ∩ (𝐵 × 𝐵))(𝐻‘𝑦)))) | 
| 13 | 12 | pm5.32i 454 | 
. 2
⊢ ((𝐻:𝐴–1-1-onto→𝐵 ∧ ∀𝑥 ∈ 𝐴 ∀𝑦 ∈ 𝐴 (𝑥𝑅𝑦 ↔ (𝐻‘𝑥)𝑆(𝐻‘𝑦))) ↔ (𝐻:𝐴–1-1-onto→𝐵 ∧ ∀𝑥 ∈ 𝐴 ∀𝑦 ∈ 𝐴 (𝑥𝑅𝑦 ↔ (𝐻‘𝑥)(𝑆 ∩ (𝐵 × 𝐵))(𝐻‘𝑦)))) | 
| 14 |   | df-isom 5267 | 
. 2
⊢ (𝐻 Isom 𝑅, 𝑆 (𝐴, 𝐵) ↔ (𝐻:𝐴–1-1-onto→𝐵 ∧ ∀𝑥 ∈ 𝐴 ∀𝑦 ∈ 𝐴 (𝑥𝑅𝑦 ↔ (𝐻‘𝑥)𝑆(𝐻‘𝑦)))) | 
| 15 |   | df-isom 5267 | 
. 2
⊢ (𝐻 Isom 𝑅, (𝑆 ∩ (𝐵 × 𝐵))(𝐴, 𝐵) ↔ (𝐻:𝐴–1-1-onto→𝐵 ∧ ∀𝑥 ∈ 𝐴 ∀𝑦 ∈ 𝐴 (𝑥𝑅𝑦 ↔ (𝐻‘𝑥)(𝑆 ∩ (𝐵 × 𝐵))(𝐻‘𝑦)))) | 
| 16 | 13, 14, 15 | 3bitr4i 212 | 
1
⊢ (𝐻 Isom 𝑅, 𝑆 (𝐴, 𝐵) ↔ 𝐻 Isom 𝑅, (𝑆 ∩ (𝐵 × 𝐵))(𝐴, 𝐵)) |