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Definition df-en 7159
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 7166. (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 7155 . 2
2 vx . . . . . 6
32cv 1653 . . . . 5
4 vy . . . . . 6
54cv 1653 . . . . 5
6 vf . . . . . 6
76cv 1653 . . . . 5
83, 5, 7wf1o 5500 . . . 4
98, 6wex 1551 . . 3
109, 2, 4copab 4300 . 2
111, 10wceq 1654 1
Colors of variables: wff set class
This definition is referenced by:  relen  7163  bren  7166  enssdom  7181
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