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Mirrors > Home > MPE Home > Th. List > df-doma | Structured version Visualization version GIF version |
Description: Definition of the domain extractor for an arrow. (Contributed by FL, 24-Oct-2007.) (Revised by Mario Carneiro, 11-Jan-2017.) |
Ref | Expression |
---|---|
df-doma | ⊢ doma = (1st ∘ 1st ) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | cdoma 17392 | . 2 class doma | |
2 | c1st 7712 | . . 3 class 1st | |
3 | 2, 2 | ccom 5529 | . 2 class (1st ∘ 1st ) |
4 | 1, 3 | wceq 1542 | 1 wff doma = (1st ∘ 1st ) |
Colors of variables: wff setvar class |
This definition is referenced by: homadm 17412 dmaf 17421 |
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