MPE Home Metamath Proof Explorer < Previous   Next >
Nearby theorems
Mirrors  >  Home  >  MPE Home  >  Th. List  >  df-doma Structured version   Visualization version   GIF version

Definition df-doma 16881
Description: Definition of the domain extractor for an arrow. (Contributed by FL, 24-Oct-2007.) (Revised by Mario Carneiro, 11-Jan-2017.)
Assertion
Ref Expression
df-doma doma = (1st ∘ 1st )

Detailed syntax breakdown of Definition df-doma
StepHypRef Expression
1 cdoma 16877 . 2 class doma
2 c1st 7317 . . 3 class 1st
32, 2ccom 5254 . 2 class (1st ∘ 1st )
41, 3wceq 1631 1 wff doma = (1st ∘ 1st )
Colors of variables: wff setvar class
This definition is referenced by:  homadm  16897  dmaf  16906
  Copyright terms: Public domain W3C validator