Metamath Proof Explorer

Theorem scottss

Description: Scott's trick produces a subset of the input class. (Contributed by Rohan Ridenour, 11-Aug-2023)

Ref Expression
Assertion scottss 
|- Scott A C_ A

Proof

Step Hyp Ref Expression
1 df-scott 
 |-  Scott A = { x e. A | A. y e. A ( rank ` x ) C_ ( rank ` y ) }
2 1 ssrab3 
 |-  Scott A C_ A