| Step | Hyp | Ref
 | Expression | 
| 1 |   | fmpoco.1 | 
. . . . . 6
⊢ ((𝜑 ∧ (𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐵)) → 𝑅 ∈ 𝐶) | 
| 2 | 1 | ralrimivva 2579 | 
. . . . 5
⊢ (𝜑 → ∀𝑥 ∈ 𝐴 ∀𝑦 ∈ 𝐵 𝑅 ∈ 𝐶) | 
| 3 |   | eqid 2196 | 
. . . . . 6
⊢ (𝑥 ∈ 𝐴, 𝑦 ∈ 𝐵 ↦ 𝑅) = (𝑥 ∈ 𝐴, 𝑦 ∈ 𝐵 ↦ 𝑅) | 
| 4 | 3 | fmpo 6259 | 
. . . . 5
⊢
(∀𝑥 ∈
𝐴 ∀𝑦 ∈ 𝐵 𝑅 ∈ 𝐶 ↔ (𝑥 ∈ 𝐴, 𝑦 ∈ 𝐵 ↦ 𝑅):(𝐴 × 𝐵)⟶𝐶) | 
| 5 | 2, 4 | sylib 122 | 
. . . 4
⊢ (𝜑 → (𝑥 ∈ 𝐴, 𝑦 ∈ 𝐵 ↦ 𝑅):(𝐴 × 𝐵)⟶𝐶) | 
| 6 |   | nfcv 2339 | 
. . . . . . 7
⊢
Ⅎ𝑢𝑅 | 
| 7 |   | nfcv 2339 | 
. . . . . . 7
⊢
Ⅎ𝑣𝑅 | 
| 8 |   | nfcv 2339 | 
. . . . . . . 8
⊢
Ⅎ𝑥𝑣 | 
| 9 |   | nfcsb1v 3117 | 
. . . . . . . 8
⊢
Ⅎ𝑥⦋𝑢 / 𝑥⦌𝑅 | 
| 10 | 8, 9 | nfcsb 3122 | 
. . . . . . 7
⊢
Ⅎ𝑥⦋𝑣 / 𝑦⦌⦋𝑢 / 𝑥⦌𝑅 | 
| 11 |   | nfcsb1v 3117 | 
. . . . . . 7
⊢
Ⅎ𝑦⦋𝑣 / 𝑦⦌⦋𝑢 / 𝑥⦌𝑅 | 
| 12 |   | csbeq1a 3093 | 
. . . . . . . 8
⊢ (𝑥 = 𝑢 → 𝑅 = ⦋𝑢 / 𝑥⦌𝑅) | 
| 13 |   | csbeq1a 3093 | 
. . . . . . . 8
⊢ (𝑦 = 𝑣 → ⦋𝑢 / 𝑥⦌𝑅 = ⦋𝑣 / 𝑦⦌⦋𝑢 / 𝑥⦌𝑅) | 
| 14 | 12, 13 | sylan9eq 2249 | 
. . . . . . 7
⊢ ((𝑥 = 𝑢 ∧ 𝑦 = 𝑣) → 𝑅 = ⦋𝑣 / 𝑦⦌⦋𝑢 / 𝑥⦌𝑅) | 
| 15 | 6, 7, 10, 11, 14 | cbvmpo 6001 | 
. . . . . 6
⊢ (𝑥 ∈ 𝐴, 𝑦 ∈ 𝐵 ↦ 𝑅) = (𝑢 ∈ 𝐴, 𝑣 ∈ 𝐵 ↦ ⦋𝑣 / 𝑦⦌⦋𝑢 / 𝑥⦌𝑅) | 
| 16 |   | vex 2766 | 
. . . . . . . . . 10
⊢ 𝑢 ∈ V | 
| 17 |   | vex 2766 | 
. . . . . . . . . 10
⊢ 𝑣 ∈ V | 
| 18 | 16, 17 | op2ndd 6207 | 
. . . . . . . . 9
⊢ (𝑤 = 〈𝑢, 𝑣〉 → (2nd ‘𝑤) = 𝑣) | 
| 19 | 18 | csbeq1d 3091 | 
. . . . . . . 8
⊢ (𝑤 = 〈𝑢, 𝑣〉 → ⦋(2nd
‘𝑤) / 𝑦⦌⦋(1st
‘𝑤) / 𝑥⦌𝑅 = ⦋𝑣 / 𝑦⦌⦋(1st
‘𝑤) / 𝑥⦌𝑅) | 
| 20 | 16, 17 | op1std 6206 | 
. . . . . . . . . 10
⊢ (𝑤 = 〈𝑢, 𝑣〉 → (1st ‘𝑤) = 𝑢) | 
| 21 | 20 | csbeq1d 3091 | 
. . . . . . . . 9
⊢ (𝑤 = 〈𝑢, 𝑣〉 → ⦋(1st
‘𝑤) / 𝑥⦌𝑅 = ⦋𝑢 / 𝑥⦌𝑅) | 
| 22 | 21 | csbeq2dv 3110 | 
. . . . . . . 8
⊢ (𝑤 = 〈𝑢, 𝑣〉 → ⦋𝑣 / 𝑦⦌⦋(1st
‘𝑤) / 𝑥⦌𝑅 = ⦋𝑣 / 𝑦⦌⦋𝑢 / 𝑥⦌𝑅) | 
| 23 | 19, 22 | eqtrd 2229 | 
. . . . . . 7
⊢ (𝑤 = 〈𝑢, 𝑣〉 → ⦋(2nd
‘𝑤) / 𝑦⦌⦋(1st
‘𝑤) / 𝑥⦌𝑅 = ⦋𝑣 / 𝑦⦌⦋𝑢 / 𝑥⦌𝑅) | 
| 24 | 23 | mpompt 6014 | 
. . . . . 6
⊢ (𝑤 ∈ (𝐴 × 𝐵) ↦ ⦋(2nd
‘𝑤) / 𝑦⦌⦋(1st
‘𝑤) / 𝑥⦌𝑅) = (𝑢 ∈ 𝐴, 𝑣 ∈ 𝐵 ↦ ⦋𝑣 / 𝑦⦌⦋𝑢 / 𝑥⦌𝑅) | 
| 25 | 15, 24 | eqtr4i 2220 | 
. . . . 5
⊢ (𝑥 ∈ 𝐴, 𝑦 ∈ 𝐵 ↦ 𝑅) = (𝑤 ∈ (𝐴 × 𝐵) ↦ ⦋(2nd
‘𝑤) / 𝑦⦌⦋(1st
‘𝑤) / 𝑥⦌𝑅) | 
| 26 | 25 | fmpt 5712 | 
. . . 4
⊢
(∀𝑤 ∈
(𝐴 × 𝐵)⦋(2nd
‘𝑤) / 𝑦⦌⦋(1st
‘𝑤) / 𝑥⦌𝑅 ∈ 𝐶 ↔ (𝑥 ∈ 𝐴, 𝑦 ∈ 𝐵 ↦ 𝑅):(𝐴 × 𝐵)⟶𝐶) | 
| 27 | 5, 26 | sylibr 134 | 
. . 3
⊢ (𝜑 → ∀𝑤 ∈ (𝐴 × 𝐵)⦋(2nd ‘𝑤) / 𝑦⦌⦋(1st
‘𝑤) / 𝑥⦌𝑅 ∈ 𝐶) | 
| 28 |   | fmpoco.2 | 
. . . 4
⊢ (𝜑 → 𝐹 = (𝑥 ∈ 𝐴, 𝑦 ∈ 𝐵 ↦ 𝑅)) | 
| 29 | 28, 25 | eqtrdi 2245 | 
. . 3
⊢ (𝜑 → 𝐹 = (𝑤 ∈ (𝐴 × 𝐵) ↦ ⦋(2nd
‘𝑤) / 𝑦⦌⦋(1st
‘𝑤) / 𝑥⦌𝑅)) | 
| 30 |   | fmpoco.3 | 
. . 3
⊢ (𝜑 → 𝐺 = (𝑧 ∈ 𝐶 ↦ 𝑆)) | 
| 31 | 27, 29, 30 | fmptcos 5730 | 
. 2
⊢ (𝜑 → (𝐺 ∘ 𝐹) = (𝑤 ∈ (𝐴 × 𝐵) ↦
⦋⦋(2nd ‘𝑤) / 𝑦⦌⦋(1st
‘𝑤) / 𝑥⦌𝑅 / 𝑧⦌𝑆)) | 
| 32 | 23 | csbeq1d 3091 | 
. . . . 5
⊢ (𝑤 = 〈𝑢, 𝑣〉 →
⦋⦋(2nd ‘𝑤) / 𝑦⦌⦋(1st
‘𝑤) / 𝑥⦌𝑅 / 𝑧⦌𝑆 = ⦋⦋𝑣 / 𝑦⦌⦋𝑢 / 𝑥⦌𝑅 / 𝑧⦌𝑆) | 
| 33 | 32 | mpompt 6014 | 
. . . 4
⊢ (𝑤 ∈ (𝐴 × 𝐵) ↦
⦋⦋(2nd ‘𝑤) / 𝑦⦌⦋(1st
‘𝑤) / 𝑥⦌𝑅 / 𝑧⦌𝑆) = (𝑢 ∈ 𝐴, 𝑣 ∈ 𝐵 ↦ ⦋⦋𝑣 / 𝑦⦌⦋𝑢 / 𝑥⦌𝑅 / 𝑧⦌𝑆) | 
| 34 |   | nfcv 2339 | 
. . . . 5
⊢
Ⅎ𝑢⦋𝑅 / 𝑧⦌𝑆 | 
| 35 |   | nfcv 2339 | 
. . . . 5
⊢
Ⅎ𝑣⦋𝑅 / 𝑧⦌𝑆 | 
| 36 |   | nfcv 2339 | 
. . . . . 6
⊢
Ⅎ𝑥𝑆 | 
| 37 | 10, 36 | nfcsb 3122 | 
. . . . 5
⊢
Ⅎ𝑥⦋⦋𝑣 / 𝑦⦌⦋𝑢 / 𝑥⦌𝑅 / 𝑧⦌𝑆 | 
| 38 |   | nfcv 2339 | 
. . . . . 6
⊢
Ⅎ𝑦𝑆 | 
| 39 | 11, 38 | nfcsb 3122 | 
. . . . 5
⊢
Ⅎ𝑦⦋⦋𝑣 / 𝑦⦌⦋𝑢 / 𝑥⦌𝑅 / 𝑧⦌𝑆 | 
| 40 | 14 | csbeq1d 3091 | 
. . . . 5
⊢ ((𝑥 = 𝑢 ∧ 𝑦 = 𝑣) → ⦋𝑅 / 𝑧⦌𝑆 = ⦋⦋𝑣 / 𝑦⦌⦋𝑢 / 𝑥⦌𝑅 / 𝑧⦌𝑆) | 
| 41 | 34, 35, 37, 39, 40 | cbvmpo 6001 | 
. . . 4
⊢ (𝑥 ∈ 𝐴, 𝑦 ∈ 𝐵 ↦ ⦋𝑅 / 𝑧⦌𝑆) = (𝑢 ∈ 𝐴, 𝑣 ∈ 𝐵 ↦ ⦋⦋𝑣 / 𝑦⦌⦋𝑢 / 𝑥⦌𝑅 / 𝑧⦌𝑆) | 
| 42 | 33, 41 | eqtr4i 2220 | 
. . 3
⊢ (𝑤 ∈ (𝐴 × 𝐵) ↦
⦋⦋(2nd ‘𝑤) / 𝑦⦌⦋(1st
‘𝑤) / 𝑥⦌𝑅 / 𝑧⦌𝑆) = (𝑥 ∈ 𝐴, 𝑦 ∈ 𝐵 ↦ ⦋𝑅 / 𝑧⦌𝑆) | 
| 43 | 1 | 3impb 1201 | 
. . . . 5
⊢ ((𝜑 ∧ 𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐵) → 𝑅 ∈ 𝐶) | 
| 44 |   | nfcvd 2340 | 
. . . . . 6
⊢ (𝑅 ∈ 𝐶 → Ⅎ𝑧𝑇) | 
| 45 |   | fmpoco.4 | 
. . . . . 6
⊢ (𝑧 = 𝑅 → 𝑆 = 𝑇) | 
| 46 | 44, 45 | csbiegf 3128 | 
. . . . 5
⊢ (𝑅 ∈ 𝐶 → ⦋𝑅 / 𝑧⦌𝑆 = 𝑇) | 
| 47 | 43, 46 | syl 14 | 
. . . 4
⊢ ((𝜑 ∧ 𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐵) → ⦋𝑅 / 𝑧⦌𝑆 = 𝑇) | 
| 48 | 47 | mpoeq3dva 5986 | 
. . 3
⊢ (𝜑 → (𝑥 ∈ 𝐴, 𝑦 ∈ 𝐵 ↦ ⦋𝑅 / 𝑧⦌𝑆) = (𝑥 ∈ 𝐴, 𝑦 ∈ 𝐵 ↦ 𝑇)) | 
| 49 | 42, 48 | eqtrid 2241 | 
. 2
⊢ (𝜑 → (𝑤 ∈ (𝐴 × 𝐵) ↦
⦋⦋(2nd ‘𝑤) / 𝑦⦌⦋(1st
‘𝑤) / 𝑥⦌𝑅 / 𝑧⦌𝑆) = (𝑥 ∈ 𝐴, 𝑦 ∈ 𝐵 ↦ 𝑇)) | 
| 50 | 31, 49 | eqtrd 2229 | 
1
⊢ (𝜑 → (𝐺 ∘ 𝐹) = (𝑥 ∈ 𝐴, 𝑦 ∈ 𝐵 ↦ 𝑇)) |