Metamath Proof Explorer


Theorem sraring

Description: Condition for a subring algebra to be a ring. (Contributed by Thierry Arnoux, 24-Jul-2023)

Ref Expression
Hypotheses sraring.1 𝐴 = ( ( subringAlg ‘ 𝑅 ) ‘ 𝑉 )
sraring.2 𝐵 = ( Base ‘ 𝑅 )
Assertion sraring ( ( 𝑅 ∈ Ring ∧ 𝑉𝐵 ) → 𝐴 ∈ Ring )

Proof

Step Hyp Ref Expression
1 sraring.1 𝐴 = ( ( subringAlg ‘ 𝑅 ) ‘ 𝑉 )
2 sraring.2 𝐵 = ( Base ‘ 𝑅 )
3 2 a1i ( 𝑉𝐵𝐵 = ( Base ‘ 𝑅 ) )
4 1 a1i ( 𝑉𝐵𝐴 = ( ( subringAlg ‘ 𝑅 ) ‘ 𝑉 ) )
5 id ( 𝑉𝐵𝑉𝐵 )
6 5 2 sseqtrdi ( 𝑉𝐵𝑉 ⊆ ( Base ‘ 𝑅 ) )
7 4 6 srabase ( 𝑉𝐵 → ( Base ‘ 𝑅 ) = ( Base ‘ 𝐴 ) )
8 2 7 syl5eq ( 𝑉𝐵𝐵 = ( Base ‘ 𝐴 ) )
9 4 6 sraaddg ( 𝑉𝐵 → ( +g𝑅 ) = ( +g𝐴 ) )
10 9 oveqdr ( ( 𝑉𝐵 ∧ ( 𝑥𝐵𝑦𝐵 ) ) → ( 𝑥 ( +g𝑅 ) 𝑦 ) = ( 𝑥 ( +g𝐴 ) 𝑦 ) )
11 4 6 sramulr ( 𝑉𝐵 → ( .r𝑅 ) = ( .r𝐴 ) )
12 11 oveqdr ( ( 𝑉𝐵 ∧ ( 𝑥𝐵𝑦𝐵 ) ) → ( 𝑥 ( .r𝑅 ) 𝑦 ) = ( 𝑥 ( .r𝐴 ) 𝑦 ) )
13 3 8 10 12 ringpropd ( 𝑉𝐵 → ( 𝑅 ∈ Ring ↔ 𝐴 ∈ Ring ) )
14 13 biimpac ( ( 𝑅 ∈ Ring ∧ 𝑉𝐵 ) → 𝐴 ∈ Ring )