Database
ZF (ZERMELO-FRAENKEL) SET THEORY
ZF Set Theory - add the Axiom of Union
Infinite Cartesian products
undifixp
Next ⟩
mptelixpg
Metamath Proof Explorer
Ascii
Unicode
Theorem
undifixp
Description:
Union of two projections of a cartesian product.
(Contributed by
FL
, 7-Nov-2011)
Ref
Expression
Assertion
undifixp
⨉
⨉
⨉
⊢
F
∈
⨉
x
∈
B
C
∧
G
∈
⨉
x
∈
A
∖
B
C
∧
B
⊆
A
→
F
∪
G
∈
⨉
x
∈
A
C
Proof
Step
Hyp
Ref
Expression
1
unexg
⨉
⨉
⊢
F
∈
⨉
x
∈
B
C
∧
G
∈
⨉
x
∈
A
∖
B
C
→
F
∪
G
∈
V
2
1
3adant3
⨉
⨉
⊢
F
∈
⨉
x
∈
B
C
∧
G
∈
⨉
x
∈
A
∖
B
C
∧
B
⊆
A
→
F
∪
G
∈
V
3
ixpfn
⨉
⊢
G
∈
⨉
x
∈
A
∖
B
C
→
G
Fn
A
∖
B
4
ixpfn
⨉
⊢
F
∈
⨉
x
∈
B
C
→
F
Fn
B
5
3simpa
⊢
G
Fn
A
∖
B
∧
F
Fn
B
∧
B
⊆
A
→
G
Fn
A
∖
B
∧
F
Fn
B
6
5
ancomd
⊢
G
Fn
A
∖
B
∧
F
Fn
B
∧
B
⊆
A
→
F
Fn
B
∧
G
Fn
A
∖
B
7
disjdif
⊢
B
∩
A
∖
B
=
∅
8
fnun
⊢
F
Fn
B
∧
G
Fn
A
∖
B
∧
B
∩
A
∖
B
=
∅
→
F
∪
G
Fn
B
∪
A
∖
B
9
6
7
8
sylancl
⊢
G
Fn
A
∖
B
∧
F
Fn
B
∧
B
⊆
A
→
F
∪
G
Fn
B
∪
A
∖
B
10
undif
⊢
B
⊆
A
↔
B
∪
A
∖
B
=
A
11
10
biimpi
⊢
B
⊆
A
→
B
∪
A
∖
B
=
A
12
11
eqcomd
⊢
B
⊆
A
→
A
=
B
∪
A
∖
B
13
12
3ad2ant3
⊢
G
Fn
A
∖
B
∧
F
Fn
B
∧
B
⊆
A
→
A
=
B
∪
A
∖
B
14
13
fneq2d
⊢
G
Fn
A
∖
B
∧
F
Fn
B
∧
B
⊆
A
→
F
∪
G
Fn
A
↔
F
∪
G
Fn
B
∪
A
∖
B
15
9
14
mpbird
⊢
G
Fn
A
∖
B
∧
F
Fn
B
∧
B
⊆
A
→
F
∪
G
Fn
A
16
15
3exp
⊢
G
Fn
A
∖
B
→
F
Fn
B
→
B
⊆
A
→
F
∪
G
Fn
A
17
3
4
16
syl2imc
⨉
⨉
⊢
F
∈
⨉
x
∈
B
C
→
G
∈
⨉
x
∈
A
∖
B
C
→
B
⊆
A
→
F
∪
G
Fn
A
18
17
3imp
⨉
⨉
⊢
F
∈
⨉
x
∈
B
C
∧
G
∈
⨉
x
∈
A
∖
B
C
∧
B
⊆
A
→
F
∪
G
Fn
A
19
elixp2
⨉
⊢
F
∈
⨉
x
∈
B
C
↔
F
∈
V
∧
F
Fn
B
∧
∀
x
∈
B
F
x
∈
C
20
19
simp3bi
⨉
⊢
F
∈
⨉
x
∈
B
C
→
∀
x
∈
B
F
x
∈
C
21
fndm
⊢
G
Fn
A
∖
B
→
dom
G
=
A
∖
B
22
elndif
⊢
x
∈
B
→
¬
x
∈
A
∖
B
23
eleq2
⊢
A
∖
B
=
dom
G
→
x
∈
A
∖
B
↔
x
∈
dom
G
24
23
notbid
⊢
A
∖
B
=
dom
G
→
¬
x
∈
A
∖
B
↔
¬
x
∈
dom
G
25
24
eqcoms
⊢
dom
G
=
A
∖
B
→
¬
x
∈
A
∖
B
↔
¬
x
∈
dom
G
26
ndmfv
⊢
¬
x
∈
dom
G
→
G
x
=
∅
27
25
26
syl6bi
⊢
dom
G
=
A
∖
B
→
¬
x
∈
A
∖
B
→
G
x
=
∅
28
21
22
27
syl2im
⊢
G
Fn
A
∖
B
→
x
∈
B
→
G
x
=
∅
29
28
ralrimiv
⊢
G
Fn
A
∖
B
→
∀
x
∈
B
G
x
=
∅
30
uneq2
⊢
G
x
=
∅
→
F
x
∪
G
x
=
F
x
∪
∅
31
un0
⊢
F
x
∪
∅
=
F
x
32
eqtr
⊢
F
x
∪
G
x
=
F
x
∪
∅
∧
F
x
∪
∅
=
F
x
→
F
x
∪
G
x
=
F
x
33
eleq1
⊢
F
x
=
F
x
∪
G
x
→
F
x
∈
C
↔
F
x
∪
G
x
∈
C
34
33
biimpd
⊢
F
x
=
F
x
∪
G
x
→
F
x
∈
C
→
F
x
∪
G
x
∈
C
35
34
eqcoms
⊢
F
x
∪
G
x
=
F
x
→
F
x
∈
C
→
F
x
∪
G
x
∈
C
36
32
35
syl
⊢
F
x
∪
G
x
=
F
x
∪
∅
∧
F
x
∪
∅
=
F
x
→
F
x
∈
C
→
F
x
∪
G
x
∈
C
37
30
31
36
sylancl
⊢
G
x
=
∅
→
F
x
∈
C
→
F
x
∪
G
x
∈
C
38
37
com12
⊢
F
x
∈
C
→
G
x
=
∅
→
F
x
∪
G
x
∈
C
39
38
ral2imi
⊢
∀
x
∈
B
F
x
∈
C
→
∀
x
∈
B
G
x
=
∅
→
∀
x
∈
B
F
x
∪
G
x
∈
C
40
20
29
39
syl2imc
⨉
⊢
G
Fn
A
∖
B
→
F
∈
⨉
x
∈
B
C
→
∀
x
∈
B
F
x
∪
G
x
∈
C
41
3
40
syl
⨉
⨉
⊢
G
∈
⨉
x
∈
A
∖
B
C
→
F
∈
⨉
x
∈
B
C
→
∀
x
∈
B
F
x
∪
G
x
∈
C
42
41
impcom
⨉
⨉
⊢
F
∈
⨉
x
∈
B
C
∧
G
∈
⨉
x
∈
A
∖
B
C
→
∀
x
∈
B
F
x
∪
G
x
∈
C
43
elixp2
⨉
⊢
G
∈
⨉
x
∈
A
∖
B
C
↔
G
∈
V
∧
G
Fn
A
∖
B
∧
∀
x
∈
A
∖
B
G
x
∈
C
44
43
simp3bi
⨉
⊢
G
∈
⨉
x
∈
A
∖
B
C
→
∀
x
∈
A
∖
B
G
x
∈
C
45
fndm
⊢
F
Fn
B
→
dom
F
=
B
46
eldifn
⊢
x
∈
A
∖
B
→
¬
x
∈
B
47
eleq2
⊢
B
=
dom
F
→
x
∈
B
↔
x
∈
dom
F
48
47
notbid
⊢
B
=
dom
F
→
¬
x
∈
B
↔
¬
x
∈
dom
F
49
ndmfv
⊢
¬
x
∈
dom
F
→
F
x
=
∅
50
48
49
syl6bi
⊢
B
=
dom
F
→
¬
x
∈
B
→
F
x
=
∅
51
50
eqcoms
⊢
dom
F
=
B
→
¬
x
∈
B
→
F
x
=
∅
52
45
46
51
syl2im
⊢
F
Fn
B
→
x
∈
A
∖
B
→
F
x
=
∅
53
52
ralrimiv
⊢
F
Fn
B
→
∀
x
∈
A
∖
B
F
x
=
∅
54
uneq1
⊢
F
x
=
∅
→
F
x
∪
G
x
=
∅
∪
G
x
55
uncom
⊢
∅
∪
G
x
=
G
x
∪
∅
56
eqtr
⊢
F
x
∪
G
x
=
∅
∪
G
x
∧
∅
∪
G
x
=
G
x
∪
∅
→
F
x
∪
G
x
=
G
x
∪
∅
57
un0
⊢
G
x
∪
∅
=
G
x
58
eqtr
⊢
F
x
∪
G
x
=
G
x
∪
∅
∧
G
x
∪
∅
=
G
x
→
F
x
∪
G
x
=
G
x
59
eleq1
⊢
G
x
=
F
x
∪
G
x
→
G
x
∈
C
↔
F
x
∪
G
x
∈
C
60
59
biimpd
⊢
G
x
=
F
x
∪
G
x
→
G
x
∈
C
→
F
x
∪
G
x
∈
C
61
60
eqcoms
⊢
F
x
∪
G
x
=
G
x
→
G
x
∈
C
→
F
x
∪
G
x
∈
C
62
58
61
syl
⊢
F
x
∪
G
x
=
G
x
∪
∅
∧
G
x
∪
∅
=
G
x
→
G
x
∈
C
→
F
x
∪
G
x
∈
C
63
56
57
62
sylancl
⊢
F
x
∪
G
x
=
∅
∪
G
x
∧
∅
∪
G
x
=
G
x
∪
∅
→
G
x
∈
C
→
F
x
∪
G
x
∈
C
64
54
55
63
sylancl
⊢
F
x
=
∅
→
G
x
∈
C
→
F
x
∪
G
x
∈
C
65
64
com12
⊢
G
x
∈
C
→
F
x
=
∅
→
F
x
∪
G
x
∈
C
66
65
ral2imi
⊢
∀
x
∈
A
∖
B
G
x
∈
C
→
∀
x
∈
A
∖
B
F
x
=
∅
→
∀
x
∈
A
∖
B
F
x
∪
G
x
∈
C
67
44
53
66
syl2imc
⨉
⊢
F
Fn
B
→
G
∈
⨉
x
∈
A
∖
B
C
→
∀
x
∈
A
∖
B
F
x
∪
G
x
∈
C
68
4
67
syl
⨉
⨉
⊢
F
∈
⨉
x
∈
B
C
→
G
∈
⨉
x
∈
A
∖
B
C
→
∀
x
∈
A
∖
B
F
x
∪
G
x
∈
C
69
68
imp
⨉
⨉
⊢
F
∈
⨉
x
∈
B
C
∧
G
∈
⨉
x
∈
A
∖
B
C
→
∀
x
∈
A
∖
B
F
x
∪
G
x
∈
C
70
ralunb
⊢
∀
x
∈
B
∪
A
∖
B
F
x
∪
G
x
∈
C
↔
∀
x
∈
B
F
x
∪
G
x
∈
C
∧
∀
x
∈
A
∖
B
F
x
∪
G
x
∈
C
71
42
69
70
sylanbrc
⨉
⨉
⊢
F
∈
⨉
x
∈
B
C
∧
G
∈
⨉
x
∈
A
∖
B
C
→
∀
x
∈
B
∪
A
∖
B
F
x
∪
G
x
∈
C
72
71
ex
⨉
⨉
⊢
F
∈
⨉
x
∈
B
C
→
G
∈
⨉
x
∈
A
∖
B
C
→
∀
x
∈
B
∪
A
∖
B
F
x
∪
G
x
∈
C
73
raleq
⊢
A
=
B
∪
A
∖
B
→
∀
x
∈
A
F
x
∪
G
x
∈
C
↔
∀
x
∈
B
∪
A
∖
B
F
x
∪
G
x
∈
C
74
73
imbi2d
⨉
⨉
⊢
A
=
B
∪
A
∖
B
→
G
∈
⨉
x
∈
A
∖
B
C
→
∀
x
∈
A
F
x
∪
G
x
∈
C
↔
G
∈
⨉
x
∈
A
∖
B
C
→
∀
x
∈
B
∪
A
∖
B
F
x
∪
G
x
∈
C
75
72
74
imbitrrid
⨉
⨉
⊢
A
=
B
∪
A
∖
B
→
F
∈
⨉
x
∈
B
C
→
G
∈
⨉
x
∈
A
∖
B
C
→
∀
x
∈
A
F
x
∪
G
x
∈
C
76
75
eqcoms
⨉
⨉
⊢
B
∪
A
∖
B
=
A
→
F
∈
⨉
x
∈
B
C
→
G
∈
⨉
x
∈
A
∖
B
C
→
∀
x
∈
A
F
x
∪
G
x
∈
C
77
10
76
sylbi
⨉
⨉
⊢
B
⊆
A
→
F
∈
⨉
x
∈
B
C
→
G
∈
⨉
x
∈
A
∖
B
C
→
∀
x
∈
A
F
x
∪
G
x
∈
C
78
77
3imp231
⨉
⨉
⊢
F
∈
⨉
x
∈
B
C
∧
G
∈
⨉
x
∈
A
∖
B
C
∧
B
⊆
A
→
∀
x
∈
A
F
x
∪
G
x
∈
C
79
df-fn
⊢
G
Fn
A
∖
B
↔
Fun
G
∧
dom
G
=
A
∖
B
80
df-fn
⊢
F
Fn
B
↔
Fun
F
∧
dom
F
=
B
81
simpl
⊢
Fun
F
∧
dom
F
=
B
→
Fun
F
82
simpl
⊢
Fun
G
∧
dom
G
=
A
∖
B
→
Fun
G
83
81
82
anim12i
⊢
Fun
F
∧
dom
F
=
B
∧
Fun
G
∧
dom
G
=
A
∖
B
→
Fun
F
∧
Fun
G
84
83
3adant3
⊢
Fun
F
∧
dom
F
=
B
∧
Fun
G
∧
dom
G
=
A
∖
B
∧
B
⊆
A
→
Fun
F
∧
Fun
G
85
ineq12
⊢
dom
F
=
B
∧
dom
G
=
A
∖
B
→
dom
F
∩
dom
G
=
B
∩
A
∖
B
86
85
7
eqtrdi
⊢
dom
F
=
B
∧
dom
G
=
A
∖
B
→
dom
F
∩
dom
G
=
∅
87
86
ad2ant2l
⊢
Fun
F
∧
dom
F
=
B
∧
Fun
G
∧
dom
G
=
A
∖
B
→
dom
F
∩
dom
G
=
∅
88
87
3adant3
⊢
Fun
F
∧
dom
F
=
B
∧
Fun
G
∧
dom
G
=
A
∖
B
∧
B
⊆
A
→
dom
F
∩
dom
G
=
∅
89
fvun
⊢
Fun
F
∧
Fun
G
∧
dom
F
∩
dom
G
=
∅
→
F
∪
G
x
=
F
x
∪
G
x
90
84
88
89
syl2anc
⊢
Fun
F
∧
dom
F
=
B
∧
Fun
G
∧
dom
G
=
A
∖
B
∧
B
⊆
A
→
F
∪
G
x
=
F
x
∪
G
x
91
90
eleq1d
⊢
Fun
F
∧
dom
F
=
B
∧
Fun
G
∧
dom
G
=
A
∖
B
∧
B
⊆
A
→
F
∪
G
x
∈
C
↔
F
x
∪
G
x
∈
C
92
91
ralbidv
⊢
Fun
F
∧
dom
F
=
B
∧
Fun
G
∧
dom
G
=
A
∖
B
∧
B
⊆
A
→
∀
x
∈
A
F
∪
G
x
∈
C
↔
∀
x
∈
A
F
x
∪
G
x
∈
C
93
92
3exp
⊢
Fun
F
∧
dom
F
=
B
→
Fun
G
∧
dom
G
=
A
∖
B
→
B
⊆
A
→
∀
x
∈
A
F
∪
G
x
∈
C
↔
∀
x
∈
A
F
x
∪
G
x
∈
C
94
80
93
sylbi
⊢
F
Fn
B
→
Fun
G
∧
dom
G
=
A
∖
B
→
B
⊆
A
→
∀
x
∈
A
F
∪
G
x
∈
C
↔
∀
x
∈
A
F
x
∪
G
x
∈
C
95
94
com12
⊢
Fun
G
∧
dom
G
=
A
∖
B
→
F
Fn
B
→
B
⊆
A
→
∀
x
∈
A
F
∪
G
x
∈
C
↔
∀
x
∈
A
F
x
∪
G
x
∈
C
96
79
95
sylbi
⊢
G
Fn
A
∖
B
→
F
Fn
B
→
B
⊆
A
→
∀
x
∈
A
F
∪
G
x
∈
C
↔
∀
x
∈
A
F
x
∪
G
x
∈
C
97
3
4
96
syl2imc
⨉
⨉
⊢
F
∈
⨉
x
∈
B
C
→
G
∈
⨉
x
∈
A
∖
B
C
→
B
⊆
A
→
∀
x
∈
A
F
∪
G
x
∈
C
↔
∀
x
∈
A
F
x
∪
G
x
∈
C
98
97
3imp
⨉
⨉
⊢
F
∈
⨉
x
∈
B
C
∧
G
∈
⨉
x
∈
A
∖
B
C
∧
B
⊆
A
→
∀
x
∈
A
F
∪
G
x
∈
C
↔
∀
x
∈
A
F
x
∪
G
x
∈
C
99
78
98
mpbird
⨉
⨉
⊢
F
∈
⨉
x
∈
B
C
∧
G
∈
⨉
x
∈
A
∖
B
C
∧
B
⊆
A
→
∀
x
∈
A
F
∪
G
x
∈
C
100
elixp2
⨉
⊢
F
∪
G
∈
⨉
x
∈
A
C
↔
F
∪
G
∈
V
∧
F
∪
G
Fn
A
∧
∀
x
∈
A
F
∪
G
x
∈
C
101
2
18
99
100
syl3anbrc
⨉
⨉
⨉
⊢
F
∈
⨉
x
∈
B
C
∧
G
∈
⨉
x
∈
A
∖
B
C
∧
B
⊆
A
→
F
∪
G
∈
⨉
x
∈
A
C