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Definition df-id 5426
 Description: Define the identity relation. Definition 9.15 of [Quine] p. 64. For example, 5 I 5 and ¬ 4 I 5 (ex-id 28233). (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 5425 . 2 class I
2 vx . . . 4 setvar 𝑥
3 vy . . . 4 setvar 𝑦
42, 3weq 1964 . . 3 wff 𝑥 = 𝑦
54, 2, 3copab 5093 . 2 class {⟨𝑥, 𝑦⟩ ∣ 𝑥 = 𝑦}
61, 5wceq 1538 1 wff I = {⟨𝑥, 𝑦⟩ ∣ 𝑥 = 𝑦}
 Colors of variables: wff setvar class This definition is referenced by:  dfid4  5427  dfid3  5428  reli  5663  ideqg  5687  opabresid  5885  opabresidOLD  5887  cnvi  5968  dffun2  6337  fsplit  7802  ider  8315  epinid0  9055  bj-opelidb  34607  bj-ideqgALT  34613  bj-idreseq  34617  bj-idreseqb  34618  bj-ideqg1  34619  bj-ideqg1ALT  34620  cossssid2  35908  cossid  35920
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