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Definition df-en 7445
 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 7453. (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 7441 . 2
2 vx . . . . . 6
32cv 1369 . . . . 5
4 vy . . . . . 6
54cv 1369 . . . . 5
6 vf . . . . . 6
76cv 1369 . . . . 5
83, 5, 7wf1o 5536 . . . 4
98, 6wex 1587 . . 3
109, 2, 4copab 4466 . 2
111, 10wceq 1370 1
 Colors of variables: wff setvar class This definition is referenced by:  relen  7449  bren  7453  enssdom  7468
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