Definition df-bj-pr1 34877

Description: Definition of the first projection of a class tuple. New usage is discouraged because the precise definition is generally unimportant compared to the characteristic properties bj-pr1eq 34878, bj-pr11val 34881, bj-pr21val 34889, bj-pr1ex 34882. (Contributed by BJ, 6-Apr-2019.) (New usage is discouraged.)

Assertion

Ref	Expression
df-bj-pr1	⊢ pr1 𝐴 = (∅ Proj 𝐴)

Detailed syntax breakdown of Definition df-bj-pr1

Step	Hyp	Ref	Expression
1		cA	. . 3 class 𝐴
2	1	bj-cpr1 34876	. 2 class pr1 𝐴
3		c0 4223	. . 3 class ∅
4	3, 1	bj-cproj 34866	. 2 class (∅ Proj 𝐴)
5	2, 4	wceq 1543	1 wff pr1 𝐴 = (∅ Proj 𝐴)

This definition is referenced by:  bj-pr1eq  34878  bj-pr1un  34879  bj-pr1val  34880  bj-pr1ex  34882