Database
ZF (ZERMELO-FRAENKEL) SET THEORY
ZF Set Theory - start with the Axiom of Extensionality
Disjointness
disjxun
Next ⟩
disjss3
Metamath Proof Explorer
Ascii
Unicode
Theorem
disjxun
Description:
The union of two disjoint collections.
(Contributed by
Mario Carneiro
, 14-Nov-2016)
Ref
Expression
Hypothesis
disjxun.1
⊢
x
=
y
→
C
=
D
Assertion
disjxun
⊢
A
∩
B
=
∅
→
Disj
x
∈
A
∪
B
C
↔
Disj
x
∈
A
C
∧
Disj
x
∈
B
C
∧
∀
x
∈
A
∀
y
∈
B
C
∩
D
=
∅
Proof
Step
Hyp
Ref
Expression
1
disjxun.1
⊢
x
=
y
→
C
=
D
2
disjel
⊢
A
∩
B
=
∅
∧
x
∈
A
→
¬
x
∈
B
3
eleq1w
⊢
x
=
y
→
x
∈
B
↔
y
∈
B
4
3
notbid
⊢
x
=
y
→
¬
x
∈
B
↔
¬
y
∈
B
5
2
4
syl5ibcom
⊢
A
∩
B
=
∅
∧
x
∈
A
→
x
=
y
→
¬
y
∈
B
6
5
con2d
⊢
A
∩
B
=
∅
∧
x
∈
A
→
y
∈
B
→
¬
x
=
y
7
6
impr
⊢
A
∩
B
=
∅
∧
x
∈
A
∧
y
∈
B
→
¬
x
=
y
8
biorf
⊢
¬
x
=
y
→
C
∩
D
=
∅
↔
x
=
y
∨
C
∩
D
=
∅
9
7
8
syl
⊢
A
∩
B
=
∅
∧
x
∈
A
∧
y
∈
B
→
C
∩
D
=
∅
↔
x
=
y
∨
C
∩
D
=
∅
10
9
bicomd
⊢
A
∩
B
=
∅
∧
x
∈
A
∧
y
∈
B
→
x
=
y
∨
C
∩
D
=
∅
↔
C
∩
D
=
∅
11
10
2ralbidva
⊢
A
∩
B
=
∅
→
∀
x
∈
A
∀
y
∈
B
x
=
y
∨
C
∩
D
=
∅
↔
∀
x
∈
A
∀
y
∈
B
C
∩
D
=
∅
12
11
anbi2d
⊢
A
∩
B
=
∅
→
∀
x
∈
A
∀
y
∈
A
x
=
y
∨
C
∩
D
=
∅
∧
∀
x
∈
A
∀
y
∈
B
x
=
y
∨
C
∩
D
=
∅
↔
∀
x
∈
A
∀
y
∈
A
x
=
y
∨
C
∩
D
=
∅
∧
∀
x
∈
A
∀
y
∈
B
C
∩
D
=
∅
13
ralunb
⊢
∀
y
∈
A
∪
B
x
=
y
∨
C
∩
D
=
∅
↔
∀
y
∈
A
x
=
y
∨
C
∩
D
=
∅
∧
∀
y
∈
B
x
=
y
∨
C
∩
D
=
∅
14
13
ralbii
⊢
∀
x
∈
A
∀
y
∈
A
∪
B
x
=
y
∨
C
∩
D
=
∅
↔
∀
x
∈
A
∀
y
∈
A
x
=
y
∨
C
∩
D
=
∅
∧
∀
y
∈
B
x
=
y
∨
C
∩
D
=
∅
15
nfv
⊢
Ⅎ
z
∀
y
∈
A
∪
B
x
=
y
∨
C
∩
D
=
∅
16
nfcv
⊢
Ⅎ
_
x
A
∪
B
17
nfv
⊢
Ⅎ
x
z
=
w
18
nfcsb1v
⦋
⦌
⊢
Ⅎ
_
x
⦋
z
/
x
⦌
C
19
nfcsb1v
⦋
⦌
⊢
Ⅎ
_
x
⦋
w
/
x
⦌
C
20
18
19
nfin
⦋
⦌
⦋
⦌
⊢
Ⅎ
_
x
⦋
z
/
x
⦌
C
∩
⦋
w
/
x
⦌
C
21
20
nfeq1
⦋
⦌
⦋
⦌
⊢
Ⅎ
x
⦋
z
/
x
⦌
C
∩
⦋
w
/
x
⦌
C
=
∅
22
17
21
nfor
⦋
⦌
⦋
⦌
⊢
Ⅎ
x
z
=
w
∨
⦋
z
/
x
⦌
C
∩
⦋
w
/
x
⦌
C
=
∅
23
16
22
nfralw
⦋
⦌
⦋
⦌
⊢
Ⅎ
x
∀
w
∈
A
∪
B
z
=
w
∨
⦋
z
/
x
⦌
C
∩
⦋
w
/
x
⦌
C
=
∅
24
equequ2
⊢
w
=
y
→
x
=
w
↔
x
=
y
25
nfcv
⊢
Ⅎ
_
x
y
26
nfcv
⊢
Ⅎ
_
x
D
27
25
26
1
csbhypf
⦋
⦌
⊢
w
=
y
→
⦋
w
/
x
⦌
C
=
D
28
27
ineq2d
⦋
⦌
⊢
w
=
y
→
C
∩
⦋
w
/
x
⦌
C
=
C
∩
D
29
28
eqeq1d
⦋
⦌
⊢
w
=
y
→
C
∩
⦋
w
/
x
⦌
C
=
∅
↔
C
∩
D
=
∅
30
24
29
orbi12d
⦋
⦌
⊢
w
=
y
→
x
=
w
∨
C
∩
⦋
w
/
x
⦌
C
=
∅
↔
x
=
y
∨
C
∩
D
=
∅
31
30
cbvralvw
⦋
⦌
⊢
∀
w
∈
A
∪
B
x
=
w
∨
C
∩
⦋
w
/
x
⦌
C
=
∅
↔
∀
y
∈
A
∪
B
x
=
y
∨
C
∩
D
=
∅
32
equequ1
⊢
x
=
z
→
x
=
w
↔
z
=
w
33
csbeq1a
⦋
⦌
⊢
x
=
z
→
C
=
⦋
z
/
x
⦌
C
34
33
ineq1d
⦋
⦌
⦋
⦌
⦋
⦌
⊢
x
=
z
→
C
∩
⦋
w
/
x
⦌
C
=
⦋
z
/
x
⦌
C
∩
⦋
w
/
x
⦌
C
35
34
eqeq1d
⦋
⦌
⦋
⦌
⦋
⦌
⊢
x
=
z
→
C
∩
⦋
w
/
x
⦌
C
=
∅
↔
⦋
z
/
x
⦌
C
∩
⦋
w
/
x
⦌
C
=
∅
36
32
35
orbi12d
⦋
⦌
⦋
⦌
⦋
⦌
⊢
x
=
z
→
x
=
w
∨
C
∩
⦋
w
/
x
⦌
C
=
∅
↔
z
=
w
∨
⦋
z
/
x
⦌
C
∩
⦋
w
/
x
⦌
C
=
∅
37
36
ralbidv
⦋
⦌
⦋
⦌
⦋
⦌
⊢
x
=
z
→
∀
w
∈
A
∪
B
x
=
w
∨
C
∩
⦋
w
/
x
⦌
C
=
∅
↔
∀
w
∈
A
∪
B
z
=
w
∨
⦋
z
/
x
⦌
C
∩
⦋
w
/
x
⦌
C
=
∅
38
31
37
bitr3id
⦋
⦌
⦋
⦌
⊢
x
=
z
→
∀
y
∈
A
∪
B
x
=
y
∨
C
∩
D
=
∅
↔
∀
w
∈
A
∪
B
z
=
w
∨
⦋
z
/
x
⦌
C
∩
⦋
w
/
x
⦌
C
=
∅
39
15
23
38
cbvralw
⦋
⦌
⦋
⦌
⊢
∀
x
∈
A
∀
y
∈
A
∪
B
x
=
y
∨
C
∩
D
=
∅
↔
∀
z
∈
A
∀
w
∈
A
∪
B
z
=
w
∨
⦋
z
/
x
⦌
C
∩
⦋
w
/
x
⦌
C
=
∅
40
r19.26
⊢
∀
x
∈
A
∀
y
∈
A
x
=
y
∨
C
∩
D
=
∅
∧
∀
y
∈
B
x
=
y
∨
C
∩
D
=
∅
↔
∀
x
∈
A
∀
y
∈
A
x
=
y
∨
C
∩
D
=
∅
∧
∀
x
∈
A
∀
y
∈
B
x
=
y
∨
C
∩
D
=
∅
41
14
39
40
3bitr3i
⦋
⦌
⦋
⦌
⊢
∀
z
∈
A
∀
w
∈
A
∪
B
z
=
w
∨
⦋
z
/
x
⦌
C
∩
⦋
w
/
x
⦌
C
=
∅
↔
∀
x
∈
A
∀
y
∈
A
x
=
y
∨
C
∩
D
=
∅
∧
∀
x
∈
A
∀
y
∈
B
x
=
y
∨
C
∩
D
=
∅
42
1
disjor
⊢
Disj
x
∈
A
C
↔
∀
x
∈
A
∀
y
∈
A
x
=
y
∨
C
∩
D
=
∅
43
42
anbi1i
⊢
Disj
x
∈
A
C
∧
∀
x
∈
A
∀
y
∈
B
C
∩
D
=
∅
↔
∀
x
∈
A
∀
y
∈
A
x
=
y
∨
C
∩
D
=
∅
∧
∀
x
∈
A
∀
y
∈
B
C
∩
D
=
∅
44
12
41
43
3bitr4g
⦋
⦌
⦋
⦌
⊢
A
∩
B
=
∅
→
∀
z
∈
A
∀
w
∈
A
∪
B
z
=
w
∨
⦋
z
/
x
⦌
C
∩
⦋
w
/
x
⦌
C
=
∅
↔
Disj
x
∈
A
C
∧
∀
x
∈
A
∀
y
∈
B
C
∩
D
=
∅
45
nfv
⦋
⦌
⊢
Ⅎ
w
z
=
x
∨
⦋
z
/
x
⦌
C
∩
C
=
∅
46
equequ2
⊢
x
=
w
→
z
=
x
↔
z
=
w
47
csbeq1a
⦋
⦌
⊢
x
=
w
→
C
=
⦋
w
/
x
⦌
C
48
47
ineq2d
⦋
⦌
⦋
⦌
⦋
⦌
⊢
x
=
w
→
⦋
z
/
x
⦌
C
∩
C
=
⦋
z
/
x
⦌
C
∩
⦋
w
/
x
⦌
C
49
48
eqeq1d
⦋
⦌
⦋
⦌
⦋
⦌
⊢
x
=
w
→
⦋
z
/
x
⦌
C
∩
C
=
∅
↔
⦋
z
/
x
⦌
C
∩
⦋
w
/
x
⦌
C
=
∅
50
46
49
orbi12d
⦋
⦌
⦋
⦌
⦋
⦌
⊢
x
=
w
→
z
=
x
∨
⦋
z
/
x
⦌
C
∩
C
=
∅
↔
z
=
w
∨
⦋
z
/
x
⦌
C
∩
⦋
w
/
x
⦌
C
=
∅
51
45
22
50
cbvralw
⦋
⦌
⦋
⦌
⦋
⦌
⊢
∀
x
∈
A
z
=
x
∨
⦋
z
/
x
⦌
C
∩
C
=
∅
↔
∀
w
∈
A
z
=
w
∨
⦋
z
/
x
⦌
C
∩
⦋
w
/
x
⦌
C
=
∅
52
equequ1
⊢
z
=
y
→
z
=
x
↔
y
=
x
53
equcom
⊢
y
=
x
↔
x
=
y
54
52
53
bitrdi
⊢
z
=
y
→
z
=
x
↔
x
=
y
55
25
26
1
csbhypf
⦋
⦌
⊢
z
=
y
→
⦋
z
/
x
⦌
C
=
D
56
55
ineq1d
⦋
⦌
⊢
z
=
y
→
⦋
z
/
x
⦌
C
∩
C
=
D
∩
C
57
incom
⊢
D
∩
C
=
C
∩
D
58
56
57
eqtrdi
⦋
⦌
⊢
z
=
y
→
⦋
z
/
x
⦌
C
∩
C
=
C
∩
D
59
58
eqeq1d
⦋
⦌
⊢
z
=
y
→
⦋
z
/
x
⦌
C
∩
C
=
∅
↔
C
∩
D
=
∅
60
54
59
orbi12d
⦋
⦌
⊢
z
=
y
→
z
=
x
∨
⦋
z
/
x
⦌
C
∩
C
=
∅
↔
x
=
y
∨
C
∩
D
=
∅
61
60
ralbidv
⦋
⦌
⊢
z
=
y
→
∀
x
∈
A
z
=
x
∨
⦋
z
/
x
⦌
C
∩
C
=
∅
↔
∀
x
∈
A
x
=
y
∨
C
∩
D
=
∅
62
51
61
bitr3id
⦋
⦌
⦋
⦌
⊢
z
=
y
→
∀
w
∈
A
z
=
w
∨
⦋
z
/
x
⦌
C
∩
⦋
w
/
x
⦌
C
=
∅
↔
∀
x
∈
A
x
=
y
∨
C
∩
D
=
∅
63
62
cbvralvw
⦋
⦌
⦋
⦌
⊢
∀
z
∈
B
∀
w
∈
A
z
=
w
∨
⦋
z
/
x
⦌
C
∩
⦋
w
/
x
⦌
C
=
∅
↔
∀
y
∈
B
∀
x
∈
A
x
=
y
∨
C
∩
D
=
∅
64
ralcom
⊢
∀
y
∈
B
∀
x
∈
A
x
=
y
∨
C
∩
D
=
∅
↔
∀
x
∈
A
∀
y
∈
B
x
=
y
∨
C
∩
D
=
∅
65
63
64
bitri
⦋
⦌
⦋
⦌
⊢
∀
z
∈
B
∀
w
∈
A
z
=
w
∨
⦋
z
/
x
⦌
C
∩
⦋
w
/
x
⦌
C
=
∅
↔
∀
x
∈
A
∀
y
∈
B
x
=
y
∨
C
∩
D
=
∅
66
65
11
bitrid
⦋
⦌
⦋
⦌
⊢
A
∩
B
=
∅
→
∀
z
∈
B
∀
w
∈
A
z
=
w
∨
⦋
z
/
x
⦌
C
∩
⦋
w
/
x
⦌
C
=
∅
↔
∀
x
∈
A
∀
y
∈
B
C
∩
D
=
∅
67
66
anbi1d
⦋
⦌
⦋
⦌
⦋
⦌
⦋
⦌
⦋
⦌
⦋
⦌
⊢
A
∩
B
=
∅
→
∀
z
∈
B
∀
w
∈
A
z
=
w
∨
⦋
z
/
x
⦌
C
∩
⦋
w
/
x
⦌
C
=
∅
∧
∀
z
∈
B
∀
w
∈
B
z
=
w
∨
⦋
z
/
x
⦌
C
∩
⦋
w
/
x
⦌
C
=
∅
↔
∀
x
∈
A
∀
y
∈
B
C
∩
D
=
∅
∧
∀
z
∈
B
∀
w
∈
B
z
=
w
∨
⦋
z
/
x
⦌
C
∩
⦋
w
/
x
⦌
C
=
∅
68
ralunb
⦋
⦌
⦋
⦌
⦋
⦌
⦋
⦌
⦋
⦌
⦋
⦌
⊢
∀
w
∈
A
∪
B
z
=
w
∨
⦋
z
/
x
⦌
C
∩
⦋
w
/
x
⦌
C
=
∅
↔
∀
w
∈
A
z
=
w
∨
⦋
z
/
x
⦌
C
∩
⦋
w
/
x
⦌
C
=
∅
∧
∀
w
∈
B
z
=
w
∨
⦋
z
/
x
⦌
C
∩
⦋
w
/
x
⦌
C
=
∅
69
68
ralbii
⦋
⦌
⦋
⦌
⦋
⦌
⦋
⦌
⦋
⦌
⦋
⦌
⊢
∀
z
∈
B
∀
w
∈
A
∪
B
z
=
w
∨
⦋
z
/
x
⦌
C
∩
⦋
w
/
x
⦌
C
=
∅
↔
∀
z
∈
B
∀
w
∈
A
z
=
w
∨
⦋
z
/
x
⦌
C
∩
⦋
w
/
x
⦌
C
=
∅
∧
∀
w
∈
B
z
=
w
∨
⦋
z
/
x
⦌
C
∩
⦋
w
/
x
⦌
C
=
∅
70
r19.26
⦋
⦌
⦋
⦌
⦋
⦌
⦋
⦌
⦋
⦌
⦋
⦌
⦋
⦌
⦋
⦌
⊢
∀
z
∈
B
∀
w
∈
A
z
=
w
∨
⦋
z
/
x
⦌
C
∩
⦋
w
/
x
⦌
C
=
∅
∧
∀
w
∈
B
z
=
w
∨
⦋
z
/
x
⦌
C
∩
⦋
w
/
x
⦌
C
=
∅
↔
∀
z
∈
B
∀
w
∈
A
z
=
w
∨
⦋
z
/
x
⦌
C
∩
⦋
w
/
x
⦌
C
=
∅
∧
∀
z
∈
B
∀
w
∈
B
z
=
w
∨
⦋
z
/
x
⦌
C
∩
⦋
w
/
x
⦌
C
=
∅
71
69
70
bitri
⦋
⦌
⦋
⦌
⦋
⦌
⦋
⦌
⦋
⦌
⦋
⦌
⊢
∀
z
∈
B
∀
w
∈
A
∪
B
z
=
w
∨
⦋
z
/
x
⦌
C
∩
⦋
w
/
x
⦌
C
=
∅
↔
∀
z
∈
B
∀
w
∈
A
z
=
w
∨
⦋
z
/
x
⦌
C
∩
⦋
w
/
x
⦌
C
=
∅
∧
∀
z
∈
B
∀
w
∈
B
z
=
w
∨
⦋
z
/
x
⦌
C
∩
⦋
w
/
x
⦌
C
=
∅
72
disjors
⦋
⦌
⦋
⦌
⊢
Disj
x
∈
B
C
↔
∀
z
∈
B
∀
w
∈
B
z
=
w
∨
⦋
z
/
x
⦌
C
∩
⦋
w
/
x
⦌
C
=
∅
73
72
anbi2ci
⦋
⦌
⦋
⦌
⊢
Disj
x
∈
B
C
∧
∀
x
∈
A
∀
y
∈
B
C
∩
D
=
∅
↔
∀
x
∈
A
∀
y
∈
B
C
∩
D
=
∅
∧
∀
z
∈
B
∀
w
∈
B
z
=
w
∨
⦋
z
/
x
⦌
C
∩
⦋
w
/
x
⦌
C
=
∅
74
67
71
73
3bitr4g
⦋
⦌
⦋
⦌
⊢
A
∩
B
=
∅
→
∀
z
∈
B
∀
w
∈
A
∪
B
z
=
w
∨
⦋
z
/
x
⦌
C
∩
⦋
w
/
x
⦌
C
=
∅
↔
Disj
x
∈
B
C
∧
∀
x
∈
A
∀
y
∈
B
C
∩
D
=
∅
75
44
74
anbi12d
⦋
⦌
⦋
⦌
⦋
⦌
⦋
⦌
⊢
A
∩
B
=
∅
→
∀
z
∈
A
∀
w
∈
A
∪
B
z
=
w
∨
⦋
z
/
x
⦌
C
∩
⦋
w
/
x
⦌
C
=
∅
∧
∀
z
∈
B
∀
w
∈
A
∪
B
z
=
w
∨
⦋
z
/
x
⦌
C
∩
⦋
w
/
x
⦌
C
=
∅
↔
Disj
x
∈
A
C
∧
∀
x
∈
A
∀
y
∈
B
C
∩
D
=
∅
∧
Disj
x
∈
B
C
∧
∀
x
∈
A
∀
y
∈
B
C
∩
D
=
∅
76
disjors
⦋
⦌
⦋
⦌
⊢
Disj
x
∈
A
∪
B
C
↔
∀
z
∈
A
∪
B
∀
w
∈
A
∪
B
z
=
w
∨
⦋
z
/
x
⦌
C
∩
⦋
w
/
x
⦌
C
=
∅
77
ralunb
⦋
⦌
⦋
⦌
⦋
⦌
⦋
⦌
⦋
⦌
⦋
⦌
⊢
∀
z
∈
A
∪
B
∀
w
∈
A
∪
B
z
=
w
∨
⦋
z
/
x
⦌
C
∩
⦋
w
/
x
⦌
C
=
∅
↔
∀
z
∈
A
∀
w
∈
A
∪
B
z
=
w
∨
⦋
z
/
x
⦌
C
∩
⦋
w
/
x
⦌
C
=
∅
∧
∀
z
∈
B
∀
w
∈
A
∪
B
z
=
w
∨
⦋
z
/
x
⦌
C
∩
⦋
w
/
x
⦌
C
=
∅
78
76
77
bitri
⦋
⦌
⦋
⦌
⦋
⦌
⦋
⦌
⊢
Disj
x
∈
A
∪
B
C
↔
∀
z
∈
A
∀
w
∈
A
∪
B
z
=
w
∨
⦋
z
/
x
⦌
C
∩
⦋
w
/
x
⦌
C
=
∅
∧
∀
z
∈
B
∀
w
∈
A
∪
B
z
=
w
∨
⦋
z
/
x
⦌
C
∩
⦋
w
/
x
⦌
C
=
∅
79
df-3an
⊢
Disj
x
∈
A
C
∧
Disj
x
∈
B
C
∧
∀
x
∈
A
∀
y
∈
B
C
∩
D
=
∅
↔
Disj
x
∈
A
C
∧
Disj
x
∈
B
C
∧
∀
x
∈
A
∀
y
∈
B
C
∩
D
=
∅
80
anandir
⊢
Disj
x
∈
A
C
∧
Disj
x
∈
B
C
∧
∀
x
∈
A
∀
y
∈
B
C
∩
D
=
∅
↔
Disj
x
∈
A
C
∧
∀
x
∈
A
∀
y
∈
B
C
∩
D
=
∅
∧
Disj
x
∈
B
C
∧
∀
x
∈
A
∀
y
∈
B
C
∩
D
=
∅
81
79
80
bitri
⊢
Disj
x
∈
A
C
∧
Disj
x
∈
B
C
∧
∀
x
∈
A
∀
y
∈
B
C
∩
D
=
∅
↔
Disj
x
∈
A
C
∧
∀
x
∈
A
∀
y
∈
B
C
∩
D
=
∅
∧
Disj
x
∈
B
C
∧
∀
x
∈
A
∀
y
∈
B
C
∩
D
=
∅
82
75
78
81
3bitr4g
⊢
A
∩
B
=
∅
→
Disj
x
∈
A
∪
B
C
↔
Disj
x
∈
A
C
∧
Disj
x
∈
B
C
∧
∀
x
∈
A
∀
y
∈
B
C
∩
D
=
∅