Metamath Proof Explorer


Definition df-bj-gab

Description: Definition of generalized class abstractions: typically, x is a bound variable in A and ph and { A | x | ph } denotes "the class of A ( x ) 's such that ph ( x ) ". (Contributed by BJ, 4-Oct-2024)

Ref Expression
Assertion df-bj-gab Could not format assertion : No typesetting found for |- {{ A | x | ph }} = { y | E. x ( A = y /\ ph ) } with typecode |-

Detailed syntax breakdown

Step Hyp Ref Expression
0 cA class A
1 vx setvar x
2 wph wff φ
3 2 1 0 bj-cgab Could not format {{ A | x | ph }} : No typesetting found for class {{ A | x | ph }} with typecode class
4 vy setvar y
5 4 cv setvar y
6 0 5 wceq wff A = y
7 6 2 wa wff A = y φ
8 7 1 wex wff x A = y φ
9 8 4 cab class y | x A = y φ
10 3 9 wceq Could not format {{ A | x | ph }} = { y | E. x ( A = y /\ ph ) } : No typesetting found for wff {{ A | x | ph }} = { y | E. x ( A = y /\ ph ) } with typecode wff