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Definition df-dfat 30020
Description: Definition of the predicate that determines if some class  F is defined as function for an argument  A or, in other words, if the function value for some class  F for an argument  A is defined. We say that  F is defined at  A if a  F is a function restricted to the member  A of its domain. (Contributed by Alexander van der Vekens, 25-May-2017.)
Assertion
Ref Expression
df-dfat  |-  ( F defAt 
A  <->  ( A  e. 
dom  F  /\  Fun  ( F  |`  { A }
) ) )

Detailed syntax breakdown of Definition df-dfat
StepHypRef Expression
1 cA . . 3  class  A
2 cF . . 3  class  F
31, 2wdfat 30017 . 2  wff  F defAt  A
42cdm 4840 . . . 4  class  dom  F
51, 4wcel 1756 . . 3  wff  A  e. 
dom  F
61csn 3877 . . . . 5  class  { A }
72, 6cres 4842 . . . 4  class  ( F  |`  { A } )
87wfun 5412 . . 3  wff  Fun  ( F  |`  { A }
)
95, 8wa 369 . 2  wff  ( A  e.  dom  F  /\  Fun  ( F  |`  { A } ) )
103, 9wb 184 1  wff  ( F defAt 
A  <->  ( A  e. 
dom  F  /\  Fun  ( F  |`  { A }
) ) )
Colors of variables: wff setvar class
This definition is referenced by:  dfateq12d  30035  nfdfat  30036  dfdfat2  30037  ndmafv  30046  nfunsnafv  30048  afvpcfv0  30052  afvfvn0fveq  30056  afv0nbfvbi  30057  fnbrafvb  30060  afvelrn  30074  afvres  30078  tz6.12-afv  30079  dmfcoafv  30081  afvco2  30082  aovmpt4g  30107
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