Metamath Proof Explorer


Definition df-coll

Description: Define the collection operation. This is similar to the image set operation " , but it uses Scott's trick to ensure the output is always a set. (Contributed by Rohan Ridenour, 11-Aug-2023)

Ref Expression
Assertion df-coll F Coll A = x A Scott F x

Detailed syntax breakdown

Step Hyp Ref Expression
0 cF class F
1 cA class A
2 1 0 ccoll class F Coll A
3 vx setvar x
4 3 cv setvar x
5 4 csn class x
6 0 5 cima class F x
7 6 cscott class Scott F x
8 3 1 7 ciun class x A Scott F x
9 2 8 wceq wff F Coll A = x A Scott F x