Theorem rngqipbas

Description: The base set of the product of the quotient with a two-sided ideal and the two-sided ideal is the cartesian product of the base set of the quotient and the base set of the two-sided ideal. (Contributed by AV, 21-Feb-2025)

	Ref	Expression
Hypotheses	rng2idlring.r	⊢ ( 𝜑 → 𝑅 ∈ Rng )
	rng2idlring.i	⊢ ( 𝜑 → 𝐼 ∈ ( 2Ideal ‘ 𝑅 ) )
	rng2idlring.j	⊢ 𝐽 = ( 𝑅 ↾s 𝐼 )
	rng2idlring.u	⊢ ( 𝜑 → 𝐽 ∈ Ring )
	rng2idlring.b	⊢ 𝐵 = ( Base ‘ 𝑅 )
	rng2idlring.t	⊢ · = ( .r ‘ 𝑅 )
	rng2idlring.1	⊢ 1 = ( 1r ‘ 𝐽 )
	rngqiprngim.g	⊢ ∼ = ( 𝑅 ~QG 𝐼 )
	rngqiprngim.q	⊢ 𝑄 = ( 𝑅 /s ∼ )
	rngqiprngim.c	⊢ 𝐶 = ( Base ‘ 𝑄 )
	rngqiprngim.p	⊢ 𝑃 = ( 𝑄 ×s 𝐽 )
Assertion	rngqipbas	⊢ ( 𝜑 → ( Base ‘ 𝑃 ) = ( 𝐶 × 𝐼 ) )

Proof

Step	Hyp	Ref	Expression
1		rng2idlring.r	⊢ ( 𝜑 → 𝑅 ∈ Rng )
2		rng2idlring.i	⊢ ( 𝜑 → 𝐼 ∈ ( 2Ideal ‘ 𝑅 ) )
3		rng2idlring.j	⊢ 𝐽 = ( 𝑅 ↾s 𝐼 )
4		rng2idlring.u	⊢ ( 𝜑 → 𝐽 ∈ Ring )
5		rng2idlring.b	⊢ 𝐵 = ( Base ‘ 𝑅 )
6		rng2idlring.t	⊢ · = ( .r ‘ 𝑅 )
7		rng2idlring.1	⊢ 1 = ( 1r ‘ 𝐽 )
8		rngqiprngim.g	⊢ ∼ = ( 𝑅 ~QG 𝐼 )
9		rngqiprngim.q	⊢ 𝑄 = ( 𝑅 /s ∼ )
10		rngqiprngim.c	⊢ 𝐶 = ( Base ‘ 𝑄 )
11		rngqiprngim.p	⊢ 𝑃 = ( 𝑄 ×s 𝐽 )
12		eqid	⊢ ( Base ‘ 𝐽 ) = ( Base ‘ 𝐽 )
13	9	ovexi	⊢ 𝑄 ∈ V
14	13	a1i	⊢ ( 𝜑 → 𝑄 ∈ V )
15	11 10 12 14 4	xpsbas	⊢ ( 𝜑 → ( 𝐶 × ( Base ‘ 𝐽 ) ) = ( Base ‘ 𝑃 ) )
16	2 3 12	2idlbas	⊢ ( 𝜑 → ( Base ‘ 𝐽 ) = 𝐼 )
17	16	xpeq2d	⊢ ( 𝜑 → ( 𝐶 × ( Base ‘ 𝐽 ) ) = ( 𝐶 × 𝐼 ) )
18	15 17	eqtr3d	⊢ ( 𝜑 → ( Base ‘ 𝑃 ) = ( 𝐶 × 𝐼 ) )