Theorem rngo0cl

Description: A ring has an additive identity element. (Contributed by Steve Rodriguez, 9-Sep-2007) (New usage is discouraged.)

	Ref	Expression
Hypotheses	ring0cl.1	⊢ 𝐺 = ( 1st ‘ 𝑅 )
	ring0cl.2	⊢ 𝑋 = ran 𝐺
	ring0cl.3	⊢ 𝑍 = ( GId ‘ 𝐺 )
Assertion	rngo0cl	⊢ ( 𝑅 ∈ RingOps → 𝑍 ∈ 𝑋 )

Proof

Step	Hyp	Ref	Expression
1		ring0cl.1	⊢ 𝐺 = ( 1st ‘ 𝑅 )
2		ring0cl.2	⊢ 𝑋 = ran 𝐺
3		ring0cl.3	⊢ 𝑍 = ( GId ‘ 𝐺 )
4	1	rngogrpo	⊢ ( 𝑅 ∈ RingOps → 𝐺 ∈ GrpOp )
5	2 3	grpoidcl	⊢ ( 𝐺 ∈ GrpOp → 𝑍 ∈ 𝑋 )
6	4 5	syl	⊢ ( 𝑅 ∈ RingOps → 𝑍 ∈ 𝑋 )