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Definition df-cnv 4785
 Description: Define the converse of a class. Definition 9.12 of [Quine] p. 64. 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 SF, 5-Jan-2015.)
Assertion
Ref Expression
df-cnv A = {x, y yAx}
Distinct variable group:   x,y,A

Detailed syntax breakdown of Definition df-cnv
StepHypRef Expression
1 cA . . 3 class A
21ccnv 4771 . 2 class A
3 vy . . . . 5 setvar y
43cv 1641 . . . 4 class y
5 vx . . . . 5 setvar x
65cv 1641 . . . 4 class x
74, 6, 1wbr 4639 . . 3 wff yAx
87, 5, 3copab 4622 . 2 class {x, y yAx}
92, 8wceq 1642 1 wff A = {x, y yAx}
 Colors of variables: wff setvar class This definition is referenced by:  cnvss  4885  elcnv  4889  nfcnv  4891  brcnv  4892  cnvco  4894  cnvi  5032  cnvun  5033
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