Definition df-bj-pr1

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 , bj-pr11val , bj-pr21val , bj-pr1ex . (Contributed by BJ, 6-Apr-2019) (New usage is discouraged.)

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

Detailed syntax breakdown

Step	Hyp	Ref	Expression
0		cA	⊢ 𝐴
1	0	bj-cpr1	⊢ pr1 𝐴
2		c0	⊢ ∅
3	2 0	bj-cproj	⊢ ( ∅ Proj 𝐴 )
4	1 3	wceq	⊢ pr1 𝐴 = ( ∅ Proj 𝐴 )