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Definition df-doma 15003
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  o.  1st )

Detailed syntax breakdown of Definition df-doma
StepHypRef Expression
1 cdoma 14999 . 2  class domA
2 c1st 6678 . . 3  class  1st
32, 2ccom 4945 . 2  class  ( 1st 
o.  1st )
41, 3wceq 1370 1  wff domA 
=  ( 1st  o.  1st )
Colors of variables: wff setvar class
This definition is referenced by:  homadm  15019  dmaf  15028
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