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Definition df-cnv 4556
 Description: Define the converse of a class. Definition 9.12 of [Quine] p. 64. The converse of a binary relation swaps its arguments, i.e., if and then , as proven in brcnv 4731 (see df-br 3939 and df-rel 4555 for more on relations). For example, { 2 , 6 , 3 , 9 } = { 6 , 2 , 9 , 3 } . We use Quine's breve accent (smile) notation. Like Quine, we use it as a prefix, which eliminates the need for parentheses. Many authors use the postfix superscript "to the minus one." "Converse" is Quine's terminology; some authors call it "inverse," especially when the argument is a function. (Contributed by NM, 4-Jul-1994.)
Assertion
Ref Expression
df-cnv
Distinct variable group:   ,,

Detailed syntax breakdown of Definition df-cnv
StepHypRef Expression
1 cA . . 3
21ccnv 4547 . 2
3 vy . . . . 5
43cv 1331 . . . 4
5 vx . . . . 5
65cv 1331 . . . 4
74, 6, 1wbr 3938 . . 3
87, 5, 3copab 3997 . 2
92, 8wceq 1332 1
 Colors of variables: wff set class This definition is referenced by:  cnvss  4721  elcnv  4725  nfcnv  4727  opelcnvg  4728  csbcnvg  4732  cnvco  4733  relcnv  4926  cnvi  4952  cnvun  4953  cnvin  4955  cnvcnv3  4997
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