| Step | Hyp | Ref
 | Expression | 
| 1 |   | 1stfo 5506 | 
. . . . . . . . . . 11
⊢ 1st
:V–onto→V | 
| 2 |   | fof 5270 | 
. . . . . . . . . . 11
⊢ (1st
:V–onto→V → 1st
:V–→V) | 
| 3 | 1, 2 | ax-mp 5 | 
. . . . . . . . . 10
⊢ 1st
:V–→V | 
| 4 |   | dffn2 5225 | 
. . . . . . . . . 10
⊢ (1st Fn
V ↔ 1st :V–→V) | 
| 5 | 3, 4 | mpbir 200 | 
. . . . . . . . 9
⊢ 1st Fn
V | 
| 6 |   | ssv 3292 | 
. . . . . . . . 9
⊢ ran 1st
⊆ V | 
| 7 |   | fnco 5192 | 
. . . . . . . . 9
⊢ ((1st Fn
V ∧ 1st Fn V ∧ ran 1st ⊆ V) → (1st ∘ 1st ) Fn V) | 
| 8 | 5, 5, 6, 7 | mp3an 1277 | 
. . . . . . . 8
⊢ (1st
∘ 1st ) Fn V | 
| 9 |   | 2ndfo 5507 | 
. . . . . . . . . . . 12
⊢ 2nd
:V–onto→V | 
| 10 |   | fofn 5272 | 
. . . . . . . . . . . 12
⊢ (2nd
:V–onto→V → 2nd
Fn V) | 
| 11 | 9, 10 | ax-mp 5 | 
. . . . . . . . . . 11
⊢ 2nd Fn
V | 
| 12 |   | fnco 5192 | 
. . . . . . . . . . 11
⊢ ((2nd Fn
V ∧ 1st Fn V ∧ ran 1st ⊆ V) → (2nd ∘ 1st ) Fn V) | 
| 13 | 11, 5, 6, 12 | mp3an 1277 | 
. . . . . . . . . 10
⊢ (2nd
∘ 1st ) Fn V | 
| 14 |   | fntxp 5805 | 
. . . . . . . . . 10
⊢ (((2nd
∘ 1st ) Fn V ∧ 2nd Fn V) → ((2nd ∘ 1st ) ⊗ 2nd ) Fn (V
∩ V)) | 
| 15 | 13, 11, 14 | mp2an 653 | 
. . . . . . . . 9
⊢ ((2nd
∘ 1st ) ⊗ 2nd )
Fn (V ∩ V) | 
| 16 |   | inidm 3465 | 
. . . . . . . . . 10
⊢ (V ∩ V) =
V | 
| 17 | 16 | fneq2i 5180 | 
. . . . . . . . 9
⊢ (((2nd
∘ 1st ) ⊗ 2nd )
Fn (V ∩ V) ↔ ((2nd ∘
1st ) ⊗ 2nd ) Fn V) | 
| 18 | 15, 17 | mpbi 199 | 
. . . . . . . 8
⊢ ((2nd
∘ 1st ) ⊗ 2nd )
Fn V | 
| 19 |   | fntxp 5805 | 
. . . . . . . 8
⊢ (((1st
∘ 1st ) Fn V ∧ ((2nd ∘ 1st ) ⊗ 2nd ) Fn V)
→ ((1st ∘ 1st )
⊗ ((2nd ∘ 1st )
⊗ 2nd )) Fn (V ∩ V)) | 
| 20 | 8, 18, 19 | mp2an 653 | 
. . . . . . 7
⊢ ((1st
∘ 1st ) ⊗ ((2nd
∘ 1st ) ⊗ 2nd
)) Fn (V ∩ V) | 
| 21 | 16 | fneq2i 5180 | 
. . . . . . 7
⊢ (((1st
∘ 1st ) ⊗ ((2nd
∘ 1st ) ⊗ 2nd
)) Fn (V ∩ V) ↔ ((1st ∘
1st ) ⊗ ((2nd ∘
1st ) ⊗ 2nd )) Fn V) | 
| 22 | 20, 21 | mpbi 199 | 
. . . . . 6
⊢ ((1st
∘ 1st ) ⊗ ((2nd
∘ 1st ) ⊗ 2nd
)) Fn V | 
| 23 |   | dffn2 5225 | 
. . . . . 6
⊢ (((1st
∘ 1st ) ⊗ ((2nd
∘ 1st ) ⊗ 2nd
)) Fn V ↔ ((1st ∘
1st ) ⊗ ((2nd ∘
1st ) ⊗ 2nd )):V–→V) | 
| 24 | 22, 23 | mpbi 199 | 
. . . . 5
⊢ ((1st
∘ 1st ) ⊗ ((2nd
∘ 1st ) ⊗ 2nd
)):V–→V | 
| 25 |   | xpassenlem 6057 | 
. . . . . . . . 9
⊢ (y((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd
))x ↔ ( Proj1
 Proj1 y =  Proj1 x ∧  Proj2  Proj1 y =  Proj1  Proj2 x ∧  Proj2 y =  Proj2  Proj2 x)) | 
| 26 |   | xpassenlem 6057 | 
. . . . . . . . 9
⊢ (z((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd
))x ↔ ( Proj1
 Proj1 z =  Proj1 x ∧  Proj2  Proj1 z =  Proj1  Proj2 x ∧  Proj2 z =  Proj2  Proj2 x)) | 
| 27 |   | simp1 955 | 
. . . . . . . . . . . . . 14
⊢ (( Proj1  Proj1 y =  Proj1 x ∧  Proj2  Proj1 y =  Proj1  Proj2 x ∧  Proj2 y =  Proj2  Proj2 x) →
 Proj1  Proj1
y =  Proj1
x) | 
| 28 |   | simp1 955 | 
. . . . . . . . . . . . . 14
⊢ (( Proj1  Proj1 z =  Proj1 x ∧  Proj2  Proj1 z =  Proj1  Proj2 x ∧  Proj2 z =  Proj2  Proj2 x) →
 Proj1  Proj1
z =  Proj1
x) | 
| 29 |   | eqtr3 2372 | 
. . . . . . . . . . . . . 14
⊢ (( Proj1  Proj1 y =  Proj1 x ∧  Proj1  Proj1 z =  Proj1 x) →  Proj1  Proj1 y =  Proj1  Proj1 z) | 
| 30 | 27, 28, 29 | syl2an 463 | 
. . . . . . . . . . . . 13
⊢ ((( Proj1  Proj1 y =  Proj1 x ∧  Proj2  Proj1 y =  Proj1  Proj2 x ∧  Proj2 y =  Proj2  Proj2 x) ∧ ( Proj1  Proj1 z =  Proj1 x ∧  Proj2  Proj1 z =  Proj1  Proj2 x ∧  Proj2 z =  Proj2  Proj2 x)) →  Proj1  Proj1 y =  Proj1  Proj1 z) | 
| 31 |   | simp2 956 | 
. . . . . . . . . . . . . 14
⊢ (( Proj1  Proj1 y =  Proj1 x ∧  Proj2  Proj1 y =  Proj1  Proj2 x ∧  Proj2 y =  Proj2  Proj2 x) →
 Proj2  Proj1
y =  Proj1
 Proj2 x) | 
| 32 |   | simp2 956 | 
. . . . . . . . . . . . . 14
⊢ (( Proj1  Proj1 z =  Proj1 x ∧  Proj2  Proj1 z =  Proj1  Proj2 x ∧  Proj2 z =  Proj2  Proj2 x) →
 Proj2  Proj1
z =  Proj1
 Proj2 x) | 
| 33 |   | eqtr3 2372 | 
. . . . . . . . . . . . . 14
⊢ (( Proj2  Proj1 y =  Proj1  Proj2 x ∧  Proj2  Proj1 z =  Proj1  Proj2 x) →  Proj2  Proj1 y =  Proj2  Proj1 z) | 
| 34 | 31, 32, 33 | syl2an 463 | 
. . . . . . . . . . . . 13
⊢ ((( Proj1  Proj1 y =  Proj1 x ∧  Proj2  Proj1 y =  Proj1  Proj2 x ∧  Proj2 y =  Proj2  Proj2 x) ∧ ( Proj1  Proj1 z =  Proj1 x ∧  Proj2  Proj1 z =  Proj1  Proj2 x ∧  Proj2 z =  Proj2  Proj2 x)) →  Proj2  Proj1 y =  Proj2  Proj1 z) | 
| 35 | 30, 34 | opeq12d 4587 | 
. . . . . . . . . . . 12
⊢ ((( Proj1  Proj1 y =  Proj1 x ∧  Proj2  Proj1 y =  Proj1  Proj2 x ∧  Proj2 y =  Proj2  Proj2 x) ∧ ( Proj1  Proj1 z =  Proj1 x ∧  Proj2  Proj1 z =  Proj1  Proj2 x ∧  Proj2 z =  Proj2  Proj2 x)) → 〈 Proj1  Proj1 y,  Proj2  Proj1 y〉 = 〈 Proj1  Proj1 z,  Proj2  Proj1 z〉) | 
| 36 |   | opeq 4620 | 
. . . . . . . . . . . 12
⊢  Proj1 y = 〈 Proj1  Proj1 y,  Proj2  Proj1 y〉 | 
| 37 |   | opeq 4620 | 
. . . . . . . . . . . 12
⊢  Proj1 z = 〈 Proj1  Proj1 z,  Proj2  Proj1 z〉 | 
| 38 | 35, 36, 37 | 3eqtr4g 2410 | 
. . . . . . . . . . 11
⊢ ((( Proj1  Proj1 y =  Proj1 x ∧  Proj2  Proj1 y =  Proj1  Proj2 x ∧  Proj2 y =  Proj2  Proj2 x) ∧ ( Proj1  Proj1 z =  Proj1 x ∧  Proj2  Proj1 z =  Proj1  Proj2 x ∧  Proj2 z =  Proj2  Proj2 x)) →  Proj1
y =  Proj1
z) | 
| 39 |   | simp3 957 | 
. . . . . . . . . . . 12
⊢ (( Proj1  Proj1 y =  Proj1 x ∧  Proj2  Proj1 y =  Proj1  Proj2 x ∧  Proj2 y =  Proj2  Proj2 x) →
 Proj2 y =
 Proj2  Proj2
x) | 
| 40 |   | simp3 957 | 
. . . . . . . . . . . 12
⊢ (( Proj1  Proj1 z =  Proj1 x ∧  Proj2  Proj1 z =  Proj1  Proj2 x ∧  Proj2 z =  Proj2  Proj2 x) →
 Proj2 z =
 Proj2  Proj2
x) | 
| 41 |   | eqtr3 2372 | 
. . . . . . . . . . . 12
⊢ (( Proj2 y =  Proj2  Proj2 x ∧  Proj2 z =  Proj2  Proj2 x) →  Proj2
y =  Proj2
z) | 
| 42 | 39, 40, 41 | syl2an 463 | 
. . . . . . . . . . 11
⊢ ((( Proj1  Proj1 y =  Proj1 x ∧  Proj2  Proj1 y =  Proj1  Proj2 x ∧  Proj2 y =  Proj2  Proj2 x) ∧ ( Proj1  Proj1 z =  Proj1 x ∧  Proj2  Proj1 z =  Proj1  Proj2 x ∧  Proj2 z =  Proj2  Proj2 x)) →  Proj2
y =  Proj2
z) | 
| 43 | 38, 42 | opeq12d 4587 | 
. . . . . . . . . 10
⊢ ((( Proj1  Proj1 y =  Proj1 x ∧  Proj2  Proj1 y =  Proj1  Proj2 x ∧  Proj2 y =  Proj2  Proj2 x) ∧ ( Proj1  Proj1 z =  Proj1 x ∧  Proj2  Proj1 z =  Proj1  Proj2 x ∧  Proj2 z =  Proj2  Proj2 x)) → 〈 Proj1 y,  Proj2 y〉 = 〈 Proj1 z,  Proj2 z〉) | 
| 44 |   | opeq 4620 | 
. . . . . . . . . 10
⊢ y = 〈 Proj1 y,  Proj2 y〉 | 
| 45 |   | opeq 4620 | 
. . . . . . . . . 10
⊢ z = 〈 Proj1 z,  Proj2 z〉 | 
| 46 | 43, 44, 45 | 3eqtr4g 2410 | 
. . . . . . . . 9
⊢ ((( Proj1  Proj1 y =  Proj1 x ∧  Proj2  Proj1 y =  Proj1  Proj2 x ∧  Proj2 y =  Proj2  Proj2 x) ∧ ( Proj1  Proj1 z =  Proj1 x ∧  Proj2  Proj1 z =  Proj1  Proj2 x ∧  Proj2 z =  Proj2  Proj2 x)) → y =
z) | 
| 47 | 25, 26, 46 | syl2anb 465 | 
. . . . . . . 8
⊢ ((y((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd
))x ∧
z((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd
))x) → y = z) | 
| 48 | 47 | gen2 1547 | 
. . . . . . 7
⊢ ∀y∀z((y((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd
))x ∧
z((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd
))x) → y = z) | 
| 49 |   | breq1 4643 | 
. . . . . . . 8
⊢ (y = z →
(y((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd
))x ↔ z((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd
))x)) | 
| 50 | 49 | mo4 2237 | 
. . . . . . 7
⊢ (∃*y y((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd
))x ↔ ∀y∀z((y((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd
))x ∧
z((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd
))x) → y = z)) | 
| 51 | 48, 50 | mpbir 200 | 
. . . . . 6
⊢ ∃*y y((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd
))x | 
| 52 | 51 | ax-gen 1546 | 
. . . . 5
⊢ ∀x∃*y y((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd
))x | 
| 53 |   | dff12 5258 | 
. . . . 5
⊢ (((1st
∘ 1st ) ⊗ ((2nd
∘ 1st ) ⊗ 2nd
)):V–1-1→V ↔
(((1st ∘ 1st )
⊗ ((2nd ∘ 1st )
⊗ 2nd )):V–→V ∧
∀x∃*y y((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd
))x)) | 
| 54 | 24, 52, 53 | mpbir2an 886 | 
. . . 4
⊢ ((1st
∘ 1st ) ⊗ ((2nd
∘ 1st ) ⊗ 2nd
)):V–1-1→V | 
| 55 |   | ssv 3292 | 
. . . 4
⊢ ((A × B)
× C) ⊆ V | 
| 56 |   | f1ores 5301 | 
. . . 4
⊢ ((((1st
∘ 1st ) ⊗ ((2nd
∘ 1st ) ⊗ 2nd
)):V–1-1→V ∧ ((A ×
B) × C) ⊆ V) →
(((1st ∘ 1st )
⊗ ((2nd ∘ 1st )
⊗ 2nd )) ↾ ((A × B)
× C)):((A × B)
× C)–1-1-onto→(((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd ))
“ ((A × B) × C))) | 
| 57 | 54, 55, 56 | mp2an 653 | 
. . 3
⊢ (((1st
∘ 1st ) ⊗ ((2nd
∘ 1st ) ⊗ 2nd
)) ↾ ((A
× B) × C)):((A ×
B) × C)–1-1-onto→(((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd ))
“ ((A × B) × C)) | 
| 58 |   | vex 2863 | 
. . . . . 6
⊢ p ∈
V | 
| 59 |   | opeqex 4622 | 
. . . . . 6
⊢ (p ∈ V → ∃b∃c p = 〈b, c〉) | 
| 60 |   | rexcom4 2879 | 
. . . . . . . . . . . 12
⊢ (∃x ∈ A ∃p∃y ∈ B ∃z ∈ C (p = 〈〈x, y〉, z〉 ∧ p((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd ))〈a, 〈b, c〉〉) ↔ ∃p∃x ∈ A ∃y ∈ B ∃z ∈ C (p = 〈〈x, y〉, z〉 ∧ p((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd ))〈a, 〈b, c〉〉)) | 
| 61 |   | rexcom4 2879 | 
. . . . . . . . . . . . . 14
⊢ (∃y ∈ B ∃p∃z ∈ C (p = 〈〈x, y〉, z〉 ∧ p((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd ))〈a, 〈b, c〉〉) ↔ ∃p∃y ∈ B ∃z ∈ C (p = 〈〈x, y〉, z〉 ∧ p((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd ))〈a, 〈b, c〉〉)) | 
| 62 |   | rexcom4 2879 | 
. . . . . . . . . . . . . . . 16
⊢ (∃z ∈ C ∃p(p = 〈〈x, y〉, z〉 ∧ p((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd ))〈a, 〈b, c〉〉) ↔ ∃p∃z ∈ C (p = 〈〈x, y〉, z〉 ∧ p((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd ))〈a, 〈b, c〉〉)) | 
| 63 |   | vex 2863 | 
. . . . . . . . . . . . . . . . . . . . 21
⊢ x ∈
V | 
| 64 |   | vex 2863 | 
. . . . . . . . . . . . . . . . . . . . 21
⊢ y ∈
V | 
| 65 | 63, 64 | opex 4589 | 
. . . . . . . . . . . . . . . . . . . 20
⊢ 〈x, y〉 ∈ V | 
| 66 |   | vex 2863 | 
. . . . . . . . . . . . . . . . . . . 20
⊢ z ∈
V | 
| 67 | 65, 66 | opex 4589 | 
. . . . . . . . . . . . . . . . . . 19
⊢ 〈〈x, y〉, z〉 ∈
V | 
| 68 |   | breq1 4643 | 
. . . . . . . . . . . . . . . . . . 19
⊢ (p = 〈〈x, y〉, z〉 →
(p((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd ))〈a, 〈b, c〉〉 ↔ 〈〈x, y〉, z〉((1st
∘ 1st ) ⊗ ((2nd
∘ 1st ) ⊗ 2nd
))〈a,
〈b,
c〉〉)) | 
| 69 | 67, 68 | ceqsexv 2895 | 
. . . . . . . . . . . . . . . . . 18
⊢ (∃p(p = 〈〈x, y〉, z〉 ∧ p((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd ))〈a, 〈b, c〉〉) ↔ 〈〈x, y〉, z〉((1st
∘ 1st ) ⊗ ((2nd
∘ 1st ) ⊗ 2nd
))〈a,
〈b,
c〉〉) | 
| 70 | 65, 66 | brco1st 5778 | 
. . . . . . . . . . . . . . . . . . . . 21
⊢ (〈〈x, y〉, z〉(1st ∘ 1st )a ↔ 〈x, y〉1st a) | 
| 71 | 63, 64 | opbr1st 5502 | 
. . . . . . . . . . . . . . . . . . . . 21
⊢ (〈x, y〉1st
a ↔ x = a) | 
| 72 | 70, 71 | bitri 240 | 
. . . . . . . . . . . . . . . . . . . 20
⊢ (〈〈x, y〉, z〉(1st ∘ 1st )a ↔ x =
a) | 
| 73 |   | trtxp 5782 | 
. . . . . . . . . . . . . . . . . . . . 21
⊢ (〈〈x, y〉, z〉((2nd ∘ 1st ) ⊗ 2nd )〈b, c〉 ↔ (〈〈x, y〉, z〉(2nd ∘ 1st )b ∧ 〈〈x, y〉, z〉2nd c)) | 
| 74 |   | brco 4884 | 
. . . . . . . . . . . . . . . . . . . . . . 23
⊢ (〈〈x, y〉, z〉(2nd ∘ 1st )b ↔ ∃t(〈〈x, y〉, z〉1st t ∧ t2nd b)) | 
| 75 | 65, 66 | opbr1st 5502 | 
. . . . . . . . . . . . . . . . . . . . . . . . . 26
⊢ (〈〈x, y〉, z〉1st t ↔ 〈x, y〉 = t) | 
| 76 |   | eqcom 2355 | 
. . . . . . . . . . . . . . . . . . . . . . . . . 26
⊢ (〈x, y〉 = t ↔ t =
〈x,
y〉) | 
| 77 | 75, 76 | bitri 240 | 
. . . . . . . . . . . . . . . . . . . . . . . . 25
⊢ (〈〈x, y〉, z〉1st t ↔ t =
〈x,
y〉) | 
| 78 | 77 | anbi1i 676 | 
. . . . . . . . . . . . . . . . . . . . . . . 24
⊢ ((〈〈x, y〉, z〉1st t ∧ t2nd b) ↔ (t =
〈x,
y〉 ∧ t2nd b)) | 
| 79 | 78 | exbii 1582 | 
. . . . . . . . . . . . . . . . . . . . . . 23
⊢ (∃t(〈〈x, y〉, z〉1st t ∧ t2nd b) ↔ ∃t(t = 〈x, y〉 ∧ t2nd b)) | 
| 80 |   | breq1 4643 | 
. . . . . . . . . . . . . . . . . . . . . . . . 25
⊢ (t = 〈x, y〉 → (t2nd b ↔ 〈x, y〉2nd b)) | 
| 81 | 65, 80 | ceqsexv 2895 | 
. . . . . . . . . . . . . . . . . . . . . . . 24
⊢ (∃t(t = 〈x, y〉 ∧ t2nd b) ↔ 〈x, y〉2nd
b) | 
| 82 | 63, 64 | opbr2nd 5503 | 
. . . . . . . . . . . . . . . . . . . . . . . 24
⊢ (〈x, y〉2nd
b ↔ y = b) | 
| 83 | 81, 82 | bitri 240 | 
. . . . . . . . . . . . . . . . . . . . . . 23
⊢ (∃t(t = 〈x, y〉 ∧ t2nd b) ↔ y =
b) | 
| 84 | 74, 79, 83 | 3bitri 262 | 
. . . . . . . . . . . . . . . . . . . . . 22
⊢ (〈〈x, y〉, z〉(2nd ∘ 1st )b ↔ y =
b) | 
| 85 | 65, 66 | opbr2nd 5503 | 
. . . . . . . . . . . . . . . . . . . . . 22
⊢ (〈〈x, y〉, z〉2nd c ↔ z =
c) | 
| 86 | 84, 85 | anbi12i 678 | 
. . . . . . . . . . . . . . . . . . . . 21
⊢ ((〈〈x, y〉, z〉(2nd ∘ 1st )b ∧ 〈〈x, y〉, z〉2nd c) ↔ (y =
b ∧
z = c)) | 
| 87 | 73, 86 | bitri 240 | 
. . . . . . . . . . . . . . . . . . . 20
⊢ (〈〈x, y〉, z〉((2nd ∘ 1st ) ⊗ 2nd )〈b, c〉 ↔
(y = b
∧ z =
c)) | 
| 88 | 72, 87 | anbi12i 678 | 
. . . . . . . . . . . . . . . . . . 19
⊢ ((〈〈x, y〉, z〉(1st ∘ 1st )a ∧ 〈〈x, y〉, z〉((2nd ∘ 1st ) ⊗ 2nd )〈b, c〉) ↔
(x = a
∧ (y =
b ∧
z = c))) | 
| 89 |   | trtxp 5782 | 
. . . . . . . . . . . . . . . . . . 19
⊢ (〈〈x, y〉, z〉((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd ))〈a, 〈b, c〉〉 ↔ (〈〈x, y〉, z〉(1st
∘ 1st )a ∧ 〈〈x, y〉, z〉((2nd ∘ 1st ) ⊗ 2nd )〈b, c〉)) | 
| 90 |   | 3anass 938 | 
. . . . . . . . . . . . . . . . . . 19
⊢ ((x = a ∧ y = b ∧ z = c) ↔
(x = a
∧ (y =
b ∧
z = c))) | 
| 91 | 88, 89, 90 | 3bitr4i 268 | 
. . . . . . . . . . . . . . . . . 18
⊢ (〈〈x, y〉, z〉((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd ))〈a, 〈b, c〉〉 ↔ (x =
a ∧
y = b
∧ z =
c)) | 
| 92 | 69, 91 | bitri 240 | 
. . . . . . . . . . . . . . . . 17
⊢ (∃p(p = 〈〈x, y〉, z〉 ∧ p((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd ))〈a, 〈b, c〉〉) ↔ (x =
a ∧
y = b
∧ z =
c)) | 
| 93 | 92 | rexbii 2640 | 
. . . . . . . . . . . . . . . 16
⊢ (∃z ∈ C ∃p(p = 〈〈x, y〉, z〉 ∧ p((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd ))〈a, 〈b, c〉〉) ↔ ∃z ∈ C (x = a ∧ y = b ∧ z = c)) | 
| 94 | 62, 93 | bitr3i 242 | 
. . . . . . . . . . . . . . 15
⊢ (∃p∃z ∈ C (p = 〈〈x, y〉, z〉 ∧ p((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd ))〈a, 〈b, c〉〉) ↔ ∃z ∈ C (x = a ∧ y = b ∧ z = c)) | 
| 95 | 94 | rexbii 2640 | 
. . . . . . . . . . . . . 14
⊢ (∃y ∈ B ∃p∃z ∈ C (p = 〈〈x, y〉, z〉 ∧ p((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd ))〈a, 〈b, c〉〉) ↔ ∃y ∈ B ∃z ∈ C (x = a ∧ y = b ∧ z = c)) | 
| 96 | 61, 95 | bitr3i 242 | 
. . . . . . . . . . . . 13
⊢ (∃p∃y ∈ B ∃z ∈ C (p = 〈〈x, y〉, z〉 ∧ p((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd ))〈a, 〈b, c〉〉) ↔ ∃y ∈ B ∃z ∈ C (x = a ∧ y = b ∧ z = c)) | 
| 97 | 96 | rexbii 2640 | 
. . . . . . . . . . . 12
⊢ (∃x ∈ A ∃p∃y ∈ B ∃z ∈ C (p = 〈〈x, y〉, z〉 ∧ p((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd ))〈a, 〈b, c〉〉) ↔ ∃x ∈ A ∃y ∈ B ∃z ∈ C (x = a ∧ y = b ∧ z = c)) | 
| 98 | 60, 97 | bitr3i 242 | 
. . . . . . . . . . 11
⊢ (∃p∃x ∈ A ∃y ∈ B ∃z ∈ C (p = 〈〈x, y〉, z〉 ∧ p((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd ))〈a, 〈b, c〉〉) ↔ ∃x ∈ A ∃y ∈ B ∃z ∈ C (x = a ∧ y = b ∧ z = c)) | 
| 99 |   | 3reeanv 2780 | 
. . . . . . . . . . 11
⊢ (∃x ∈ A ∃y ∈ B ∃z ∈ C (x = a ∧ y = b ∧ z = c) ↔
(∃x
∈ A
x = a
∧ ∃y ∈ B y = b ∧ ∃z ∈ C z = c)) | 
| 100 | 98, 99 | bitri 240 | 
. . . . . . . . . 10
⊢ (∃p∃x ∈ A ∃y ∈ B ∃z ∈ C (p = 〈〈x, y〉, z〉 ∧ p((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd ))〈a, 〈b, c〉〉) ↔ (∃x ∈ A x = a ∧ ∃y ∈ B y = b ∧ ∃z ∈ C z = c)) | 
| 101 |   | r19.41v 2765 | 
. . . . . . . . . . . 12
⊢ (∃x ∈ A (∃y ∈ B ∃z ∈ C p = 〈〈x, y〉, z〉 ∧ p((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd ))〈a, 〈b, c〉〉) ↔ (∃x ∈ A ∃y ∈ B ∃z ∈ C p = 〈〈x, y〉, z〉 ∧ p((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd ))〈a, 〈b, c〉〉)) | 
| 102 |   | r19.41v 2765 | 
. . . . . . . . . . . . . . 15
⊢ (∃z ∈ C (p = 〈〈x, y〉, z〉 ∧ p((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd ))〈a, 〈b, c〉〉) ↔ (∃z ∈ C p = 〈〈x, y〉, z〉 ∧ p((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd ))〈a, 〈b, c〉〉)) | 
| 103 | 102 | rexbii 2640 | 
. . . . . . . . . . . . . 14
⊢ (∃y ∈ B ∃z ∈ C (p = 〈〈x, y〉, z〉 ∧ p((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd ))〈a, 〈b, c〉〉) ↔ ∃y ∈ B (∃z ∈ C p = 〈〈x, y〉, z〉 ∧ p((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd ))〈a, 〈b, c〉〉)) | 
| 104 |   | r19.41v 2765 | 
. . . . . . . . . . . . . 14
⊢ (∃y ∈ B (∃z ∈ C p = 〈〈x, y〉, z〉 ∧ p((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd ))〈a, 〈b, c〉〉) ↔ (∃y ∈ B ∃z ∈ C p = 〈〈x, y〉, z〉 ∧ p((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd ))〈a, 〈b, c〉〉)) | 
| 105 | 103, 104 | bitri 240 | 
. . . . . . . . . . . . 13
⊢ (∃y ∈ B ∃z ∈ C (p = 〈〈x, y〉, z〉 ∧ p((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd ))〈a, 〈b, c〉〉) ↔ (∃y ∈ B ∃z ∈ C p = 〈〈x, y〉, z〉 ∧ p((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd ))〈a, 〈b, c〉〉)) | 
| 106 | 105 | rexbii 2640 | 
. . . . . . . . . . . 12
⊢ (∃x ∈ A ∃y ∈ B ∃z ∈ C (p = 〈〈x, y〉, z〉 ∧ p((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd ))〈a, 〈b, c〉〉) ↔ ∃x ∈ A (∃y ∈ B ∃z ∈ C p = 〈〈x, y〉, z〉 ∧ p((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd ))〈a, 〈b, c〉〉)) | 
| 107 |   | elxp2 4803 | 
. . . . . . . . . . . . . 14
⊢ (p ∈ ((A × B)
× C) ↔ ∃t ∈ (A ×
B)∃z ∈ C p = 〈t, z〉) | 
| 108 |   | df-rex 2621 | 
. . . . . . . . . . . . . 14
⊢ (∃t ∈ (A ×
B)∃z ∈ C p = 〈t, z〉 ↔ ∃t(t ∈ (A × B)
∧ ∃z ∈ C p = 〈t, z〉)) | 
| 109 |   | rexcom4 2879 | 
. . . . . . . . . . . . . . 15
⊢ (∃x ∈ A ∃t∃y ∈ B ∃z ∈ C (t = 〈x, y〉 ∧ p = 〈t, z〉) ↔ ∃t∃x ∈ A ∃y ∈ B ∃z ∈ C (t = 〈x, y〉 ∧ p = 〈t, z〉)) | 
| 110 |   | opeq1 4579 | 
. . . . . . . . . . . . . . . . . . . . . 22
⊢ (t = 〈x, y〉 → 〈t, z〉 = 〈〈x, y〉, z〉) | 
| 111 | 110 | eqeq2d 2364 | 
. . . . . . . . . . . . . . . . . . . . 21
⊢ (t = 〈x, y〉 → (p =
〈t,
z〉 ↔
p = 〈〈x, y〉, z〉)) | 
| 112 | 65, 111 | ceqsexv 2895 | 
. . . . . . . . . . . . . . . . . . . 20
⊢ (∃t(t = 〈x, y〉 ∧ p = 〈t, z〉) ↔ p =
〈〈x, y〉, z〉) | 
| 113 | 112 | rexbii 2640 | 
. . . . . . . . . . . . . . . . . . 19
⊢ (∃z ∈ C ∃t(t = 〈x, y〉 ∧ p = 〈t, z〉) ↔ ∃z ∈ C p = 〈〈x, y〉, z〉) | 
| 114 |   | rexcom4 2879 | 
. . . . . . . . . . . . . . . . . . 19
⊢ (∃z ∈ C ∃t(t = 〈x, y〉 ∧ p = 〈t, z〉) ↔ ∃t∃z ∈ C (t = 〈x, y〉 ∧ p = 〈t, z〉)) | 
| 115 | 113, 114 | bitr3i 242 | 
. . . . . . . . . . . . . . . . . 18
⊢ (∃z ∈ C p = 〈〈x, y〉, z〉 ↔ ∃t∃z ∈ C (t = 〈x, y〉 ∧ p = 〈t, z〉)) | 
| 116 | 115 | rexbii 2640 | 
. . . . . . . . . . . . . . . . 17
⊢ (∃y ∈ B ∃z ∈ C p = 〈〈x, y〉, z〉 ↔ ∃y ∈ B ∃t∃z ∈ C (t = 〈x, y〉 ∧ p = 〈t, z〉)) | 
| 117 |   | rexcom4 2879 | 
. . . . . . . . . . . . . . . . 17
⊢ (∃y ∈ B ∃t∃z ∈ C (t = 〈x, y〉 ∧ p = 〈t, z〉) ↔ ∃t∃y ∈ B ∃z ∈ C (t = 〈x, y〉 ∧ p = 〈t, z〉)) | 
| 118 | 116, 117 | bitri 240 | 
. . . . . . . . . . . . . . . 16
⊢ (∃y ∈ B ∃z ∈ C p = 〈〈x, y〉, z〉 ↔ ∃t∃y ∈ B ∃z ∈ C (t = 〈x, y〉 ∧ p = 〈t, z〉)) | 
| 119 | 118 | rexbii 2640 | 
. . . . . . . . . . . . . . 15
⊢ (∃x ∈ A ∃y ∈ B ∃z ∈ C p = 〈〈x, y〉, z〉 ↔ ∃x ∈ A ∃t∃y ∈ B ∃z ∈ C (t = 〈x, y〉 ∧ p = 〈t, z〉)) | 
| 120 |   | r19.41v 2765 | 
. . . . . . . . . . . . . . . . 17
⊢ (∃x ∈ A (∃y ∈ B t = 〈x, y〉 ∧ ∃z ∈ C p = 〈t, z〉) ↔ (∃x ∈ A ∃y ∈ B t = 〈x, y〉 ∧ ∃z ∈ C p = 〈t, z〉)) | 
| 121 |   | reeanv 2779 | 
. . . . . . . . . . . . . . . . . 18
⊢ (∃y ∈ B ∃z ∈ C (t = 〈x, y〉 ∧ p = 〈t, z〉) ↔ (∃y ∈ B t = 〈x, y〉 ∧ ∃z ∈ C p = 〈t, z〉)) | 
| 122 | 121 | rexbii 2640 | 
. . . . . . . . . . . . . . . . 17
⊢ (∃x ∈ A ∃y ∈ B ∃z ∈ C (t = 〈x, y〉 ∧ p = 〈t, z〉) ↔ ∃x ∈ A (∃y ∈ B t = 〈x, y〉 ∧ ∃z ∈ C p = 〈t, z〉)) | 
| 123 |   | elxp2 4803 | 
. . . . . . . . . . . . . . . . . 18
⊢ (t ∈ (A × B)
↔ ∃x ∈ A ∃y ∈ B t = 〈x, y〉) | 
| 124 | 123 | anbi1i 676 | 
. . . . . . . . . . . . . . . . 17
⊢ ((t ∈ (A × B)
∧ ∃z ∈ C p = 〈t, z〉) ↔ (∃x ∈ A ∃y ∈ B t = 〈x, y〉 ∧ ∃z ∈ C p = 〈t, z〉)) | 
| 125 | 120, 122,
124 | 3bitr4ri 269 | 
. . . . . . . . . . . . . . . 16
⊢ ((t ∈ (A × B)
∧ ∃z ∈ C p = 〈t, z〉) ↔ ∃x ∈ A ∃y ∈ B ∃z ∈ C (t = 〈x, y〉 ∧ p = 〈t, z〉)) | 
| 126 | 125 | exbii 1582 | 
. . . . . . . . . . . . . . 15
⊢ (∃t(t ∈ (A × B)
∧ ∃z ∈ C p = 〈t, z〉) ↔ ∃t∃x ∈ A ∃y ∈ B ∃z ∈ C (t = 〈x, y〉 ∧ p = 〈t, z〉)) | 
| 127 | 109, 119,
126 | 3bitr4ri 269 | 
. . . . . . . . . . . . . 14
⊢ (∃t(t ∈ (A × B)
∧ ∃z ∈ C p = 〈t, z〉) ↔ ∃x ∈ A ∃y ∈ B ∃z ∈ C p = 〈〈x, y〉, z〉) | 
| 128 | 107, 108,
127 | 3bitri 262 | 
. . . . . . . . . . . . 13
⊢ (p ∈ ((A × B)
× C) ↔ ∃x ∈ A ∃y ∈ B ∃z ∈ C p = 〈〈x, y〉, z〉) | 
| 129 | 128 | anbi1i 676 | 
. . . . . . . . . . . 12
⊢ ((p ∈ ((A × B)
× C) ∧ p((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd ))〈a, 〈b, c〉〉) ↔ (∃x ∈ A ∃y ∈ B ∃z ∈ C p = 〈〈x, y〉, z〉 ∧ p((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd ))〈a, 〈b, c〉〉)) | 
| 130 | 101, 106,
129 | 3bitr4ri 269 | 
. . . . . . . . . . 11
⊢ ((p ∈ ((A × B)
× C) ∧ p((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd ))〈a, 〈b, c〉〉) ↔ ∃x ∈ A ∃y ∈ B ∃z ∈ C (p = 〈〈x, y〉, z〉 ∧ p((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd ))〈a, 〈b, c〉〉)) | 
| 131 | 130 | exbii 1582 | 
. . . . . . . . . 10
⊢ (∃p(p ∈ ((A × B)
× C) ∧ p((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd ))〈a, 〈b, c〉〉) ↔ ∃p∃x ∈ A ∃y ∈ B ∃z ∈ C (p = 〈〈x, y〉, z〉 ∧ p((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd ))〈a, 〈b, c〉〉)) | 
| 132 |   | risset 2662 | 
. . . . . . . . . . 11
⊢ (a ∈ A ↔ ∃x ∈ A x = a) | 
| 133 |   | risset 2662 | 
. . . . . . . . . . 11
⊢ (b ∈ B ↔ ∃y ∈ B y = b) | 
| 134 |   | risset 2662 | 
. . . . . . . . . . 11
⊢ (c ∈ C ↔ ∃z ∈ C z = c) | 
| 135 | 132, 133,
134 | 3anbi123i 1140 | 
. . . . . . . . . 10
⊢ ((a ∈ A ∧ b ∈ B ∧ c ∈ C) ↔ (∃x ∈ A x = a ∧ ∃y ∈ B y = b ∧ ∃z ∈ C z = c)) | 
| 136 | 100, 131,
135 | 3bitr4i 268 | 
. . . . . . . . 9
⊢ (∃p(p ∈ ((A × B)
× C) ∧ p((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd ))〈a, 〈b, c〉〉) ↔ (a
∈ A ∧ b ∈ B ∧ c ∈ C)) | 
| 137 |   | elima2 4756 | 
. . . . . . . . 9
⊢ (〈a, 〈b, c〉〉 ∈
(((1st ∘ 1st )
⊗ ((2nd ∘ 1st )
⊗ 2nd )) “ ((A
× B) × C)) ↔ ∃p(p ∈ ((A × B)
× C) ∧ p((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd ))〈a, 〈b, c〉〉)) | 
| 138 |   | opelxp 4812 | 
. . . . . . . . . . 11
⊢ (〈b, c〉 ∈ (B ×
C) ↔ (b ∈ B ∧ c ∈ C)) | 
| 139 | 138 | anbi2i 675 | 
. . . . . . . . . 10
⊢ ((a ∈ A ∧ 〈b, c〉 ∈ (B ×
C)) ↔ (a ∈ A ∧ (b ∈ B ∧ c ∈ C))) | 
| 140 |   | opelxp 4812 | 
. . . . . . . . . 10
⊢ (〈a, 〈b, c〉〉 ∈ (A × (B
× C)) ↔ (a ∈ A ∧ 〈b, c〉 ∈ (B ×
C))) | 
| 141 |   | 3anass 938 | 
. . . . . . . . . 10
⊢ ((a ∈ A ∧ b ∈ B ∧ c ∈ C) ↔ (a
∈ A ∧ (b ∈ B ∧ c ∈ C))) | 
| 142 | 139, 140,
141 | 3bitr4i 268 | 
. . . . . . . . 9
⊢ (〈a, 〈b, c〉〉 ∈ (A × (B
× C)) ↔ (a ∈ A ∧ b ∈ B ∧ c ∈ C)) | 
| 143 | 136, 137,
142 | 3bitr4i 268 | 
. . . . . . . 8
⊢ (〈a, 〈b, c〉〉 ∈
(((1st ∘ 1st )
⊗ ((2nd ∘ 1st )
⊗ 2nd )) “ ((A
× B) × C)) ↔ 〈a, 〈b, c〉〉 ∈ (A × (B
× C))) | 
| 144 |   | opeq2 4580 | 
. . . . . . . . . 10
⊢ (p = 〈b, c〉 → 〈a, p〉 = 〈a, 〈b, c〉〉) | 
| 145 | 144 | eleq1d 2419 | 
. . . . . . . . 9
⊢ (p = 〈b, c〉 → (〈a, p〉 ∈ (((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd ))
“ ((A × B) × C))
↔ 〈a, 〈b, c〉〉 ∈ (((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd ))
“ ((A × B) × C)))) | 
| 146 | 144 | eleq1d 2419 | 
. . . . . . . . 9
⊢ (p = 〈b, c〉 → (〈a, p〉 ∈ (A ×
(B × C)) ↔ 〈a, 〈b, c〉〉 ∈ (A × (B
× C)))) | 
| 147 | 145, 146 | bibi12d 312 | 
. . . . . . . 8
⊢ (p = 〈b, c〉 → ((〈a, p〉 ∈ (((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd ))
“ ((A × B) × C))
↔ 〈a, p〉 ∈ (A × (B
× C))) ↔ (〈a, 〈b, c〉〉 ∈
(((1st ∘ 1st )
⊗ ((2nd ∘ 1st )
⊗ 2nd )) “ ((A
× B) × C)) ↔ 〈a, 〈b, c〉〉 ∈ (A × (B
× C))))) | 
| 148 | 143, 147 | mpbiri 224 | 
. . . . . . 7
⊢ (p = 〈b, c〉 → (〈a, p〉 ∈ (((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd ))
“ ((A × B) × C))
↔ 〈a, p〉 ∈ (A × (B
× C)))) | 
| 149 | 148 | exlimivv 1635 | 
. . . . . 6
⊢ (∃b∃c p = 〈b, c〉 → (〈a, p〉 ∈ (((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd ))
“ ((A × B) × C))
↔ 〈a, p〉 ∈ (A × (B
× C)))) | 
| 150 | 58, 59, 149 | mp2b 9 | 
. . . . 5
⊢ (〈a, p〉 ∈ (((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd ))
“ ((A × B) × C))
↔ 〈a, p〉 ∈ (A × (B
× C))) | 
| 151 | 150 | eqrelriv 4851 | 
. . . 4
⊢ (((1st
∘ 1st ) ⊗ ((2nd
∘ 1st ) ⊗ 2nd
)) “ ((A × B) × C)) =
(A × (B × C)) | 
| 152 |   | f1oeq3 5284 | 
. . . 4
⊢ ((((1st
∘ 1st ) ⊗ ((2nd
∘ 1st ) ⊗ 2nd
)) “ ((A × B) × C)) =
(A × (B × C))
→ ((((1st ∘ 1st )
⊗ ((2nd ∘ 1st )
⊗ 2nd )) ↾ ((A × B)
× C)):((A × B)
× C)–1-1-onto→(((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd ))
“ ((A × B) × C))
↔ (((1st ∘ 1st )
⊗ ((2nd ∘ 1st )
⊗ 2nd )) ↾ ((A × B)
× C)):((A × B)
× C)–1-1-onto→(A ×
(B × C)))) | 
| 153 | 151, 152 | ax-mp 5 | 
. . 3
⊢ ((((1st
∘ 1st ) ⊗ ((2nd
∘ 1st ) ⊗ 2nd
)) ↾ ((A
× B) × C)):((A ×
B) × C)–1-1-onto→(((1st ∘ 1st ) ⊗ ((2nd ∘ 1st ) ⊗ 2nd ))
“ ((A × B) × C))
↔ (((1st ∘ 1st )
⊗ ((2nd ∘ 1st )
⊗ 2nd )) ↾ ((A × B)
× C)):((A × B)
× C)–1-1-onto→(A ×
(B × C))) | 
| 154 | 57, 153 | mpbi 199 | 
. 2
⊢ (((1st
∘ 1st ) ⊗ ((2nd
∘ 1st ) ⊗ 2nd
)) ↾ ((A
× B) × C)):((A ×
B) × C)–1-1-onto→(A ×
(B × C)) | 
| 155 |   | 1stex 4740 | 
. . . . . 6
⊢ 1st
∈ V | 
| 156 | 155, 155 | coex 4751 | 
. . . . 5
⊢ (1st
∘ 1st ) ∈ V | 
| 157 |   | 2ndex 5113 | 
. . . . . . 7
⊢ 2nd
∈ V | 
| 158 | 157, 155 | coex 4751 | 
. . . . . 6
⊢ (2nd
∘ 1st ) ∈ V | 
| 159 | 158, 157 | txpex 5786 | 
. . . . 5
⊢ ((2nd
∘ 1st ) ⊗ 2nd )
∈ V | 
| 160 | 156, 159 | txpex 5786 | 
. . . 4
⊢ ((1st
∘ 1st ) ⊗ ((2nd
∘ 1st ) ⊗ 2nd
)) ∈ V | 
| 161 |   | xpassen.1 | 
. . . . . 6
⊢ A ∈
V | 
| 162 |   | xpassen.2 | 
. . . . . 6
⊢ B ∈
V | 
| 163 | 161, 162 | xpex 5116 | 
. . . . 5
⊢ (A × B)
∈ V | 
| 164 |   | xpassen.3 | 
. . . . 5
⊢ C ∈
V | 
| 165 | 163, 164 | xpex 5116 | 
. . . 4
⊢ ((A × B)
× C) ∈ V | 
| 166 | 160, 165 | resex 5118 | 
. . 3
⊢ (((1st
∘ 1st ) ⊗ ((2nd
∘ 1st ) ⊗ 2nd
)) ↾ ((A
× B) × C)) ∈
V | 
| 167 | 166 | f1oen 6034 | 
. 2
⊢ ((((1st
∘ 1st ) ⊗ ((2nd
∘ 1st ) ⊗ 2nd
)) ↾ ((A
× B) × C)):((A ×
B) × C)–1-1-onto→(A ×
(B × C)) → ((A
× B) × C) ≈ (A
× (B × C))) | 
| 168 | 154, 167 | ax-mp 5 | 
1
⊢ ((A × B)
× C) ≈ (A × (B
× C)) |