| Step | Hyp | Ref
 | Expression | 
| 1 |   | simpl 109 | 
. . . 4
⊢ ((𝐺:𝐵–1-1-onto→𝐶 ∧ ∀𝑧 ∈ 𝐵 ∀𝑤 ∈ 𝐵 (𝑧𝑆𝑤 ↔ (𝐺‘𝑧)𝑇(𝐺‘𝑤))) → 𝐺:𝐵–1-1-onto→𝐶) | 
| 2 |   | simpl 109 | 
. . . 4
⊢ ((𝐻:𝐴–1-1-onto→𝐵 ∧ ∀𝑥 ∈ 𝐴 ∀𝑦 ∈ 𝐴 (𝑥𝑅𝑦 ↔ (𝐻‘𝑥)𝑆(𝐻‘𝑦))) → 𝐻:𝐴–1-1-onto→𝐵) | 
| 3 |   | f1oco 5527 | 
. . . 4
⊢ ((𝐺:𝐵–1-1-onto→𝐶 ∧ 𝐻:𝐴–1-1-onto→𝐵) → (𝐺 ∘ 𝐻):𝐴–1-1-onto→𝐶) | 
| 4 | 1, 2, 3 | syl2anr 290 | 
. . 3
⊢ (((𝐻:𝐴–1-1-onto→𝐵 ∧ ∀𝑥 ∈ 𝐴 ∀𝑦 ∈ 𝐴 (𝑥𝑅𝑦 ↔ (𝐻‘𝑥)𝑆(𝐻‘𝑦))) ∧ (𝐺:𝐵–1-1-onto→𝐶 ∧ ∀𝑧 ∈ 𝐵 ∀𝑤 ∈ 𝐵 (𝑧𝑆𝑤 ↔ (𝐺‘𝑧)𝑇(𝐺‘𝑤)))) → (𝐺 ∘ 𝐻):𝐴–1-1-onto→𝐶) | 
| 5 |   | f1of 5504 | 
. . . . . . . . . . . 12
⊢ (𝐻:𝐴–1-1-onto→𝐵 → 𝐻:𝐴⟶𝐵) | 
| 6 | 5 | ad2antrr 488 | 
. . . . . . . . . . 11
⊢ (((𝐻:𝐴–1-1-onto→𝐵 ∧ (𝐺:𝐵–1-1-onto→𝐶 ∧ ∀𝑧 ∈ 𝐵 ∀𝑤 ∈ 𝐵 (𝑧𝑆𝑤 ↔ (𝐺‘𝑧)𝑇(𝐺‘𝑤)))) ∧ (𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐴)) → 𝐻:𝐴⟶𝐵) | 
| 7 |   | simprl 529 | 
. . . . . . . . . . 11
⊢ (((𝐻:𝐴–1-1-onto→𝐵 ∧ (𝐺:𝐵–1-1-onto→𝐶 ∧ ∀𝑧 ∈ 𝐵 ∀𝑤 ∈ 𝐵 (𝑧𝑆𝑤 ↔ (𝐺‘𝑧)𝑇(𝐺‘𝑤)))) ∧ (𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐴)) → 𝑥 ∈ 𝐴) | 
| 8 | 6, 7 | ffvelcdmd 5698 | 
. . . . . . . . . 10
⊢ (((𝐻:𝐴–1-1-onto→𝐵 ∧ (𝐺:𝐵–1-1-onto→𝐶 ∧ ∀𝑧 ∈ 𝐵 ∀𝑤 ∈ 𝐵 (𝑧𝑆𝑤 ↔ (𝐺‘𝑧)𝑇(𝐺‘𝑤)))) ∧ (𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐴)) → (𝐻‘𝑥) ∈ 𝐵) | 
| 9 |   | simprr 531 | 
. . . . . . . . . . 11
⊢ (((𝐻:𝐴–1-1-onto→𝐵 ∧ (𝐺:𝐵–1-1-onto→𝐶 ∧ ∀𝑧 ∈ 𝐵 ∀𝑤 ∈ 𝐵 (𝑧𝑆𝑤 ↔ (𝐺‘𝑧)𝑇(𝐺‘𝑤)))) ∧ (𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐴)) → 𝑦 ∈ 𝐴) | 
| 10 | 6, 9 | ffvelcdmd 5698 | 
. . . . . . . . . 10
⊢ (((𝐻:𝐴–1-1-onto→𝐵 ∧ (𝐺:𝐵–1-1-onto→𝐶 ∧ ∀𝑧 ∈ 𝐵 ∀𝑤 ∈ 𝐵 (𝑧𝑆𝑤 ↔ (𝐺‘𝑧)𝑇(𝐺‘𝑤)))) ∧ (𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐴)) → (𝐻‘𝑦) ∈ 𝐵) | 
| 11 |   | simplrr 536 | 
. . . . . . . . . 10
⊢ (((𝐻:𝐴–1-1-onto→𝐵 ∧ (𝐺:𝐵–1-1-onto→𝐶 ∧ ∀𝑧 ∈ 𝐵 ∀𝑤 ∈ 𝐵 (𝑧𝑆𝑤 ↔ (𝐺‘𝑧)𝑇(𝐺‘𝑤)))) ∧ (𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐴)) → ∀𝑧 ∈ 𝐵 ∀𝑤 ∈ 𝐵 (𝑧𝑆𝑤 ↔ (𝐺‘𝑧)𝑇(𝐺‘𝑤))) | 
| 12 |   | breq1 4036 | 
. . . . . . . . . . . 12
⊢ (𝑧 = (𝐻‘𝑥) → (𝑧𝑆𝑤 ↔ (𝐻‘𝑥)𝑆𝑤)) | 
| 13 |   | fveq2 5558 | 
. . . . . . . . . . . . 13
⊢ (𝑧 = (𝐻‘𝑥) → (𝐺‘𝑧) = (𝐺‘(𝐻‘𝑥))) | 
| 14 | 13 | breq1d 4043 | 
. . . . . . . . . . . 12
⊢ (𝑧 = (𝐻‘𝑥) → ((𝐺‘𝑧)𝑇(𝐺‘𝑤) ↔ (𝐺‘(𝐻‘𝑥))𝑇(𝐺‘𝑤))) | 
| 15 | 12, 14 | bibi12d 235 | 
. . . . . . . . . . 11
⊢ (𝑧 = (𝐻‘𝑥) → ((𝑧𝑆𝑤 ↔ (𝐺‘𝑧)𝑇(𝐺‘𝑤)) ↔ ((𝐻‘𝑥)𝑆𝑤 ↔ (𝐺‘(𝐻‘𝑥))𝑇(𝐺‘𝑤)))) | 
| 16 |   | breq2 4037 | 
. . . . . . . . . . . 12
⊢ (𝑤 = (𝐻‘𝑦) → ((𝐻‘𝑥)𝑆𝑤 ↔ (𝐻‘𝑥)𝑆(𝐻‘𝑦))) | 
| 17 |   | fveq2 5558 | 
. . . . . . . . . . . . 13
⊢ (𝑤 = (𝐻‘𝑦) → (𝐺‘𝑤) = (𝐺‘(𝐻‘𝑦))) | 
| 18 | 17 | breq2d 4045 | 
. . . . . . . . . . . 12
⊢ (𝑤 = (𝐻‘𝑦) → ((𝐺‘(𝐻‘𝑥))𝑇(𝐺‘𝑤) ↔ (𝐺‘(𝐻‘𝑥))𝑇(𝐺‘(𝐻‘𝑦)))) | 
| 19 | 16, 18 | bibi12d 235 | 
. . . . . . . . . . 11
⊢ (𝑤 = (𝐻‘𝑦) → (((𝐻‘𝑥)𝑆𝑤 ↔ (𝐺‘(𝐻‘𝑥))𝑇(𝐺‘𝑤)) ↔ ((𝐻‘𝑥)𝑆(𝐻‘𝑦) ↔ (𝐺‘(𝐻‘𝑥))𝑇(𝐺‘(𝐻‘𝑦))))) | 
| 20 | 15, 19 | rspc2va 2882 | 
. . . . . . . . . 10
⊢ ((((𝐻‘𝑥) ∈ 𝐵 ∧ (𝐻‘𝑦) ∈ 𝐵) ∧ ∀𝑧 ∈ 𝐵 ∀𝑤 ∈ 𝐵 (𝑧𝑆𝑤 ↔ (𝐺‘𝑧)𝑇(𝐺‘𝑤))) → ((𝐻‘𝑥)𝑆(𝐻‘𝑦) ↔ (𝐺‘(𝐻‘𝑥))𝑇(𝐺‘(𝐻‘𝑦)))) | 
| 21 | 8, 10, 11, 20 | syl21anc 1248 | 
. . . . . . . . 9
⊢ (((𝐻:𝐴–1-1-onto→𝐵 ∧ (𝐺:𝐵–1-1-onto→𝐶 ∧ ∀𝑧 ∈ 𝐵 ∀𝑤 ∈ 𝐵 (𝑧𝑆𝑤 ↔ (𝐺‘𝑧)𝑇(𝐺‘𝑤)))) ∧ (𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐴)) → ((𝐻‘𝑥)𝑆(𝐻‘𝑦) ↔ (𝐺‘(𝐻‘𝑥))𝑇(𝐺‘(𝐻‘𝑦)))) | 
| 22 |   | fvco3 5632 | 
. . . . . . . . . . 11
⊢ ((𝐻:𝐴⟶𝐵 ∧ 𝑥 ∈ 𝐴) → ((𝐺 ∘ 𝐻)‘𝑥) = (𝐺‘(𝐻‘𝑥))) | 
| 23 | 6, 7, 22 | syl2anc 411 | 
. . . . . . . . . 10
⊢ (((𝐻:𝐴–1-1-onto→𝐵 ∧ (𝐺:𝐵–1-1-onto→𝐶 ∧ ∀𝑧 ∈ 𝐵 ∀𝑤 ∈ 𝐵 (𝑧𝑆𝑤 ↔ (𝐺‘𝑧)𝑇(𝐺‘𝑤)))) ∧ (𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐴)) → ((𝐺 ∘ 𝐻)‘𝑥) = (𝐺‘(𝐻‘𝑥))) | 
| 24 |   | fvco3 5632 | 
. . . . . . . . . . 11
⊢ ((𝐻:𝐴⟶𝐵 ∧ 𝑦 ∈ 𝐴) → ((𝐺 ∘ 𝐻)‘𝑦) = (𝐺‘(𝐻‘𝑦))) | 
| 25 | 6, 9, 24 | syl2anc 411 | 
. . . . . . . . . 10
⊢ (((𝐻:𝐴–1-1-onto→𝐵 ∧ (𝐺:𝐵–1-1-onto→𝐶 ∧ ∀𝑧 ∈ 𝐵 ∀𝑤 ∈ 𝐵 (𝑧𝑆𝑤 ↔ (𝐺‘𝑧)𝑇(𝐺‘𝑤)))) ∧ (𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐴)) → ((𝐺 ∘ 𝐻)‘𝑦) = (𝐺‘(𝐻‘𝑦))) | 
| 26 | 23, 25 | breq12d 4046 | 
. . . . . . . . 9
⊢ (((𝐻:𝐴–1-1-onto→𝐵 ∧ (𝐺:𝐵–1-1-onto→𝐶 ∧ ∀𝑧 ∈ 𝐵 ∀𝑤 ∈ 𝐵 (𝑧𝑆𝑤 ↔ (𝐺‘𝑧)𝑇(𝐺‘𝑤)))) ∧ (𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐴)) → (((𝐺 ∘ 𝐻)‘𝑥)𝑇((𝐺 ∘ 𝐻)‘𝑦) ↔ (𝐺‘(𝐻‘𝑥))𝑇(𝐺‘(𝐻‘𝑦)))) | 
| 27 | 21, 26 | bitr4d 191 | 
. . . . . . . 8
⊢ (((𝐻:𝐴–1-1-onto→𝐵 ∧ (𝐺:𝐵–1-1-onto→𝐶 ∧ ∀𝑧 ∈ 𝐵 ∀𝑤 ∈ 𝐵 (𝑧𝑆𝑤 ↔ (𝐺‘𝑧)𝑇(𝐺‘𝑤)))) ∧ (𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐴)) → ((𝐻‘𝑥)𝑆(𝐻‘𝑦) ↔ ((𝐺 ∘ 𝐻)‘𝑥)𝑇((𝐺 ∘ 𝐻)‘𝑦))) | 
| 28 | 27 | bibi2d 232 | 
. . . . . . 7
⊢ (((𝐻:𝐴–1-1-onto→𝐵 ∧ (𝐺:𝐵–1-1-onto→𝐶 ∧ ∀𝑧 ∈ 𝐵 ∀𝑤 ∈ 𝐵 (𝑧𝑆𝑤 ↔ (𝐺‘𝑧)𝑇(𝐺‘𝑤)))) ∧ (𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐴)) → ((𝑥𝑅𝑦 ↔ (𝐻‘𝑥)𝑆(𝐻‘𝑦)) ↔ (𝑥𝑅𝑦 ↔ ((𝐺 ∘ 𝐻)‘𝑥)𝑇((𝐺 ∘ 𝐻)‘𝑦)))) | 
| 29 | 28 | 2ralbidva 2519 | 
. . . . . 6
⊢ ((𝐻:𝐴–1-1-onto→𝐵 ∧ (𝐺:𝐵–1-1-onto→𝐶 ∧ ∀𝑧 ∈ 𝐵 ∀𝑤 ∈ 𝐵 (𝑧𝑆𝑤 ↔ (𝐺‘𝑧)𝑇(𝐺‘𝑤)))) → (∀𝑥 ∈ 𝐴 ∀𝑦 ∈ 𝐴 (𝑥𝑅𝑦 ↔ (𝐻‘𝑥)𝑆(𝐻‘𝑦)) ↔ ∀𝑥 ∈ 𝐴 ∀𝑦 ∈ 𝐴 (𝑥𝑅𝑦 ↔ ((𝐺 ∘ 𝐻)‘𝑥)𝑇((𝐺 ∘ 𝐻)‘𝑦)))) | 
| 30 | 29 | biimpd 144 | 
. . . . 5
⊢ ((𝐻:𝐴–1-1-onto→𝐵 ∧ (𝐺:𝐵–1-1-onto→𝐶 ∧ ∀𝑧 ∈ 𝐵 ∀𝑤 ∈ 𝐵 (𝑧𝑆𝑤 ↔ (𝐺‘𝑧)𝑇(𝐺‘𝑤)))) → (∀𝑥 ∈ 𝐴 ∀𝑦 ∈ 𝐴 (𝑥𝑅𝑦 ↔ (𝐻‘𝑥)𝑆(𝐻‘𝑦)) → ∀𝑥 ∈ 𝐴 ∀𝑦 ∈ 𝐴 (𝑥𝑅𝑦 ↔ ((𝐺 ∘ 𝐻)‘𝑥)𝑇((𝐺 ∘ 𝐻)‘𝑦)))) | 
| 31 | 30 | impancom 260 | 
. . . 4
⊢ ((𝐻:𝐴–1-1-onto→𝐵 ∧ ∀𝑥 ∈ 𝐴 ∀𝑦 ∈ 𝐴 (𝑥𝑅𝑦 ↔ (𝐻‘𝑥)𝑆(𝐻‘𝑦))) → ((𝐺:𝐵–1-1-onto→𝐶 ∧ ∀𝑧 ∈ 𝐵 ∀𝑤 ∈ 𝐵 (𝑧𝑆𝑤 ↔ (𝐺‘𝑧)𝑇(𝐺‘𝑤))) → ∀𝑥 ∈ 𝐴 ∀𝑦 ∈ 𝐴 (𝑥𝑅𝑦 ↔ ((𝐺 ∘ 𝐻)‘𝑥)𝑇((𝐺 ∘ 𝐻)‘𝑦)))) | 
| 32 | 31 | imp 124 | 
. . 3
⊢ (((𝐻:𝐴–1-1-onto→𝐵 ∧ ∀𝑥 ∈ 𝐴 ∀𝑦 ∈ 𝐴 (𝑥𝑅𝑦 ↔ (𝐻‘𝑥)𝑆(𝐻‘𝑦))) ∧ (𝐺:𝐵–1-1-onto→𝐶 ∧ ∀𝑧 ∈ 𝐵 ∀𝑤 ∈ 𝐵 (𝑧𝑆𝑤 ↔ (𝐺‘𝑧)𝑇(𝐺‘𝑤)))) → ∀𝑥 ∈ 𝐴 ∀𝑦 ∈ 𝐴 (𝑥𝑅𝑦 ↔ ((𝐺 ∘ 𝐻)‘𝑥)𝑇((𝐺 ∘ 𝐻)‘𝑦))) | 
| 33 | 4, 32 | jca 306 | 
. 2
⊢ (((𝐻:𝐴–1-1-onto→𝐵 ∧ ∀𝑥 ∈ 𝐴 ∀𝑦 ∈ 𝐴 (𝑥𝑅𝑦 ↔ (𝐻‘𝑥)𝑆(𝐻‘𝑦))) ∧ (𝐺:𝐵–1-1-onto→𝐶 ∧ ∀𝑧 ∈ 𝐵 ∀𝑤 ∈ 𝐵 (𝑧𝑆𝑤 ↔ (𝐺‘𝑧)𝑇(𝐺‘𝑤)))) → ((𝐺 ∘ 𝐻):𝐴–1-1-onto→𝐶 ∧ ∀𝑥 ∈ 𝐴 ∀𝑦 ∈ 𝐴 (𝑥𝑅𝑦 ↔ ((𝐺 ∘ 𝐻)‘𝑥)𝑇((𝐺 ∘ 𝐻)‘𝑦)))) | 
| 34 |   | df-isom 5267 | 
. . 3
⊢ (𝐻 Isom 𝑅, 𝑆 (𝐴, 𝐵) ↔ (𝐻:𝐴–1-1-onto→𝐵 ∧ ∀𝑥 ∈ 𝐴 ∀𝑦 ∈ 𝐴 (𝑥𝑅𝑦 ↔ (𝐻‘𝑥)𝑆(𝐻‘𝑦)))) | 
| 35 |   | df-isom 5267 | 
. . 3
⊢ (𝐺 Isom 𝑆, 𝑇 (𝐵, 𝐶) ↔ (𝐺:𝐵–1-1-onto→𝐶 ∧ ∀𝑧 ∈ 𝐵 ∀𝑤 ∈ 𝐵 (𝑧𝑆𝑤 ↔ (𝐺‘𝑧)𝑇(𝐺‘𝑤)))) | 
| 36 | 34, 35 | anbi12i 460 | 
. 2
⊢ ((𝐻 Isom 𝑅, 𝑆 (𝐴, 𝐵) ∧ 𝐺 Isom 𝑆, 𝑇 (𝐵, 𝐶)) ↔ ((𝐻:𝐴–1-1-onto→𝐵 ∧ ∀𝑥 ∈ 𝐴 ∀𝑦 ∈ 𝐴 (𝑥𝑅𝑦 ↔ (𝐻‘𝑥)𝑆(𝐻‘𝑦))) ∧ (𝐺:𝐵–1-1-onto→𝐶 ∧ ∀𝑧 ∈ 𝐵 ∀𝑤 ∈ 𝐵 (𝑧𝑆𝑤 ↔ (𝐺‘𝑧)𝑇(𝐺‘𝑤))))) | 
| 37 |   | df-isom 5267 | 
. 2
⊢ ((𝐺 ∘ 𝐻) Isom 𝑅, 𝑇 (𝐴, 𝐶) ↔ ((𝐺 ∘ 𝐻):𝐴–1-1-onto→𝐶 ∧ ∀𝑥 ∈ 𝐴 ∀𝑦 ∈ 𝐴 (𝑥𝑅𝑦 ↔ ((𝐺 ∘ 𝐻)‘𝑥)𝑇((𝐺 ∘ 𝐻)‘𝑦)))) | 
| 38 | 33, 36, 37 | 3imtr4i 201 | 
1
⊢ ((𝐻 Isom 𝑅, 𝑆 (𝐴, 𝐵) ∧ 𝐺 Isom 𝑆, 𝑇 (𝐵, 𝐶)) → (𝐺 ∘ 𝐻) Isom 𝑅, 𝑇 (𝐴, 𝐶)) |