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Definition df-id 4021
Description: Define the identity relation. Definition 9.15 of [Quine] p. 64. For example, 5 I 5 and ¬ 4 I 5. (Contributed by NM, 13-Aug-1995.)
Assertion
Ref Expression
df-id I = {⟨x, y⟩ ∣ x = y}
Distinct variable group:   x,y

Detailed syntax breakdown of Definition df-id
StepHypRef Expression
1 cid 4016 . 2 class I
2 vx . . . 4 setvar x
3 vy . . . 4 setvar y
42, 3weq 1389 . . 3 wff x = y
54, 2, 3copab 3808 . 2 class {⟨x, y⟩ ∣ x = y}
61, 5wceq 1242 1 wff I = {⟨x, y⟩ ∣ x = y}
Colors of variables: wff set class
This definition is referenced by:  reli  4408  ideqg  4430  opabresid  4602  cnvi  4671  dffun2  4855  ider  6075
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