Metamath Proof Explorer


Theorem 2idlcpbl

Description: The coset equivalence relation for a two-sided ideal is compatible with ring multiplication. (Contributed by Mario Carneiro, 14-Jun-2015) (Proof shortened by AV, 31-Mar-2025)

Ref Expression
Hypotheses 2idlcpblrng.x 𝑋 = ( Base ‘ 𝑅 )
2idlcpblrng.r 𝐸 = ( 𝑅 ~QG 𝑆 )
2idlcpblrng.i 𝐼 = ( 2Ideal ‘ 𝑅 )
2idlcpblrng.t · = ( .r𝑅 )
Assertion 2idlcpbl ( ( 𝑅 ∈ Ring ∧ 𝑆𝐼 ) → ( ( 𝐴 𝐸 𝐶𝐵 𝐸 𝐷 ) → ( 𝐴 · 𝐵 ) 𝐸 ( 𝐶 · 𝐷 ) ) )

Proof

Step Hyp Ref Expression
1 2idlcpblrng.x 𝑋 = ( Base ‘ 𝑅 )
2 2idlcpblrng.r 𝐸 = ( 𝑅 ~QG 𝑆 )
3 2idlcpblrng.i 𝐼 = ( 2Ideal ‘ 𝑅 )
4 2idlcpblrng.t · = ( .r𝑅 )
5 ringrng ( 𝑅 ∈ Ring → 𝑅 ∈ Rng )
6 5 adantr ( ( 𝑅 ∈ Ring ∧ 𝑆𝐼 ) → 𝑅 ∈ Rng )
7 simpr ( ( 𝑅 ∈ Ring ∧ 𝑆𝐼 ) → 𝑆𝐼 )
8 eqid ( LIdeal ‘ 𝑅 ) = ( LIdeal ‘ 𝑅 )
9 eqid ( oppr𝑅 ) = ( oppr𝑅 )
10 eqid ( LIdeal ‘ ( oppr𝑅 ) ) = ( LIdeal ‘ ( oppr𝑅 ) )
11 8 9 10 3 2idlelb ( 𝑆𝐼 ↔ ( 𝑆 ∈ ( LIdeal ‘ 𝑅 ) ∧ 𝑆 ∈ ( LIdeal ‘ ( oppr𝑅 ) ) ) )
12 11 simplbi ( 𝑆𝐼𝑆 ∈ ( LIdeal ‘ 𝑅 ) )
13 8 lidlsubg ( ( 𝑅 ∈ Ring ∧ 𝑆 ∈ ( LIdeal ‘ 𝑅 ) ) → 𝑆 ∈ ( SubGrp ‘ 𝑅 ) )
14 12 13 sylan2 ( ( 𝑅 ∈ Ring ∧ 𝑆𝐼 ) → 𝑆 ∈ ( SubGrp ‘ 𝑅 ) )
15 1 2 3 4 2idlcpblrng ( ( 𝑅 ∈ Rng ∧ 𝑆𝐼𝑆 ∈ ( SubGrp ‘ 𝑅 ) ) → ( ( 𝐴 𝐸 𝐶𝐵 𝐸 𝐷 ) → ( 𝐴 · 𝐵 ) 𝐸 ( 𝐶 · 𝐷 ) ) )
16 6 7 14 15 syl3anc ( ( 𝑅 ∈ Ring ∧ 𝑆𝐼 ) → ( ( 𝐴 𝐸 𝐶𝐵 𝐸 𝐷 ) → ( 𝐴 · 𝐵 ) 𝐸 ( 𝐶 · 𝐷 ) ) )