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Definition df-un 3370
Description: Define the union of two classes. Definition 5.6 of [TakeutiZaring] p. 16. For example, (ex-un 22753). Contrast this operation with difference (df-dif 3368) and intersection (df-in 3372). For an alternate definition in terms of class difference, requiring no dummy variables, see dfun2 3621. For union defined in terms of intersection, see dfun3 3624. (Contributed by NM, 23-Aug-1993.)
Assertion
Ref Expression
df-un
Distinct variable groups:   ,   ,

Detailed syntax breakdown of Definition df-un
StepHypRef Expression
1 cA . . 3
2 cB . . 3
31, 2cun 3363 . 2
4 vx . . . . . 6
54cv 1669 . . . . 5
65, 1wcel 1732 . . . 4
75, 2wcel 1732 . . . 4
86, 7wo 359 . . 3
98, 4cab 2475 . 2
103, 9wceq 1670 1
Colors of variables: wff set class
This definition is referenced by:  elun  3534  nfun  3549  unipr  4130  iinuni  4280  fvclss  5973  bnj98  30708
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