Description: Alternate definition of the identity relation. (Contributed by NM, 15-Mar-2007) Use df-id when sufficient (see comment at dfid3 ). (New usage is discouraged.)
Ref | Expression | ||
---|---|---|---|
Assertion | dfid2 | |- _I = { <. x , x >. | x = x } |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | dfid3 | |- _I = { <. x , x >. | x = x } |