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Mirrors > Home > NFE Home > Th. List > cab | GIF version |
Description: Introduce the class builder or class abstraction notation ("the class of sets x such that φ is true"). Our class variables A, B, etc. range over class builders (implicitly in the case of defined class terms such as df-nul 3551). Note that a setvar variable can be expressed as a class builder per theorem cvjust 2348, justifying the assignment of setvar variables to class variables via the use of cv 1641. |
Ref | Expression |
---|---|
wph | wff φ |
vx | setvar x |
Ref | Expression |
---|---|
cab | class {x ∣ φ} |
Colors of variables: wff setvar class |
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