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Definition df-en 7222
Description: Define the equinumerosity relation. Definition of [Enderton] p. 129. We define to be a binary relation rather than a connective, so its arguments must be sets to be meaningful. This is acceptable because we do not consider equinumerosity for proper classes. We derive the usual definition as bren 7229. (Contributed by NM, 28-Mar-1998.)
Assertion
Ref Expression
df-en
Distinct variable group:   , ,

Detailed syntax breakdown of Definition df-en
StepHypRef Expression
1 cen 7218 . 2
2 vx . . . . . 6
32cv 1661 . . . . 5
4 vy . . . . . 6
54cv 1661 . . . . 5
6 vf . . . . . 6
76cv 1661 . . . . 5
83, 5, 7wf1o 5416 . . . 4
98, 6wex 1557 . . 3
109, 2, 4copab 4359 . 2
111, 10wceq 1662 1
Colors of variables: wff set class
This definition is referenced by:  relen  7226  bren  7229  enssdom  7244
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