Metamath Proof Explorer


Theorem subrgint

Description: The intersection of a nonempty collection of subrings is a subring. (Contributed by Stefan O'Rear, 30-Nov-2014) (Revised by Mario Carneiro, 7-Dec-2014)

Ref Expression
Assertion subrgint ( ( 𝑆 ⊆ ( SubRing ‘ 𝑅 ) ∧ 𝑆 ≠ ∅ ) → 𝑆 ∈ ( SubRing ‘ 𝑅 ) )

Proof

Step Hyp Ref Expression
1 subrgsubg ( 𝑟 ∈ ( SubRing ‘ 𝑅 ) → 𝑟 ∈ ( SubGrp ‘ 𝑅 ) )
2 1 ssriv ( SubRing ‘ 𝑅 ) ⊆ ( SubGrp ‘ 𝑅 )
3 sstr ( ( 𝑆 ⊆ ( SubRing ‘ 𝑅 ) ∧ ( SubRing ‘ 𝑅 ) ⊆ ( SubGrp ‘ 𝑅 ) ) → 𝑆 ⊆ ( SubGrp ‘ 𝑅 ) )
4 2 3 mpan2 ( 𝑆 ⊆ ( SubRing ‘ 𝑅 ) → 𝑆 ⊆ ( SubGrp ‘ 𝑅 ) )
5 subgint ( ( 𝑆 ⊆ ( SubGrp ‘ 𝑅 ) ∧ 𝑆 ≠ ∅ ) → 𝑆 ∈ ( SubGrp ‘ 𝑅 ) )
6 4 5 sylan ( ( 𝑆 ⊆ ( SubRing ‘ 𝑅 ) ∧ 𝑆 ≠ ∅ ) → 𝑆 ∈ ( SubGrp ‘ 𝑅 ) )
7 ssel2 ( ( 𝑆 ⊆ ( SubRing ‘ 𝑅 ) ∧ 𝑟𝑆 ) → 𝑟 ∈ ( SubRing ‘ 𝑅 ) )
8 7 adantlr ( ( ( 𝑆 ⊆ ( SubRing ‘ 𝑅 ) ∧ 𝑆 ≠ ∅ ) ∧ 𝑟𝑆 ) → 𝑟 ∈ ( SubRing ‘ 𝑅 ) )
9 eqid ( 1r𝑅 ) = ( 1r𝑅 )
10 9 subrg1cl ( 𝑟 ∈ ( SubRing ‘ 𝑅 ) → ( 1r𝑅 ) ∈ 𝑟 )
11 8 10 syl ( ( ( 𝑆 ⊆ ( SubRing ‘ 𝑅 ) ∧ 𝑆 ≠ ∅ ) ∧ 𝑟𝑆 ) → ( 1r𝑅 ) ∈ 𝑟 )
12 11 ralrimiva ( ( 𝑆 ⊆ ( SubRing ‘ 𝑅 ) ∧ 𝑆 ≠ ∅ ) → ∀ 𝑟𝑆 ( 1r𝑅 ) ∈ 𝑟 )
13 fvex ( 1r𝑅 ) ∈ V
14 13 elint2 ( ( 1r𝑅 ) ∈ 𝑆 ↔ ∀ 𝑟𝑆 ( 1r𝑅 ) ∈ 𝑟 )
15 12 14 sylibr ( ( 𝑆 ⊆ ( SubRing ‘ 𝑅 ) ∧ 𝑆 ≠ ∅ ) → ( 1r𝑅 ) ∈ 𝑆 )
16 8 adantlr ( ( ( ( 𝑆 ⊆ ( SubRing ‘ 𝑅 ) ∧ 𝑆 ≠ ∅ ) ∧ ( 𝑥 𝑆𝑦 𝑆 ) ) ∧ 𝑟𝑆 ) → 𝑟 ∈ ( SubRing ‘ 𝑅 ) )
17 simprl ( ( ( 𝑆 ⊆ ( SubRing ‘ 𝑅 ) ∧ 𝑆 ≠ ∅ ) ∧ ( 𝑥 𝑆𝑦 𝑆 ) ) → 𝑥 𝑆 )
18 elinti ( 𝑥 𝑆 → ( 𝑟𝑆𝑥𝑟 ) )
19 18 imp ( ( 𝑥 𝑆𝑟𝑆 ) → 𝑥𝑟 )
20 17 19 sylan ( ( ( ( 𝑆 ⊆ ( SubRing ‘ 𝑅 ) ∧ 𝑆 ≠ ∅ ) ∧ ( 𝑥 𝑆𝑦 𝑆 ) ) ∧ 𝑟𝑆 ) → 𝑥𝑟 )
21 simprr ( ( ( 𝑆 ⊆ ( SubRing ‘ 𝑅 ) ∧ 𝑆 ≠ ∅ ) ∧ ( 𝑥 𝑆𝑦 𝑆 ) ) → 𝑦 𝑆 )
22 elinti ( 𝑦 𝑆 → ( 𝑟𝑆𝑦𝑟 ) )
23 22 imp ( ( 𝑦 𝑆𝑟𝑆 ) → 𝑦𝑟 )
24 21 23 sylan ( ( ( ( 𝑆 ⊆ ( SubRing ‘ 𝑅 ) ∧ 𝑆 ≠ ∅ ) ∧ ( 𝑥 𝑆𝑦 𝑆 ) ) ∧ 𝑟𝑆 ) → 𝑦𝑟 )
25 eqid ( .r𝑅 ) = ( .r𝑅 )
26 25 subrgmcl ( ( 𝑟 ∈ ( SubRing ‘ 𝑅 ) ∧ 𝑥𝑟𝑦𝑟 ) → ( 𝑥 ( .r𝑅 ) 𝑦 ) ∈ 𝑟 )
27 16 20 24 26 syl3anc ( ( ( ( 𝑆 ⊆ ( SubRing ‘ 𝑅 ) ∧ 𝑆 ≠ ∅ ) ∧ ( 𝑥 𝑆𝑦 𝑆 ) ) ∧ 𝑟𝑆 ) → ( 𝑥 ( .r𝑅 ) 𝑦 ) ∈ 𝑟 )
28 27 ralrimiva ( ( ( 𝑆 ⊆ ( SubRing ‘ 𝑅 ) ∧ 𝑆 ≠ ∅ ) ∧ ( 𝑥 𝑆𝑦 𝑆 ) ) → ∀ 𝑟𝑆 ( 𝑥 ( .r𝑅 ) 𝑦 ) ∈ 𝑟 )
29 ovex ( 𝑥 ( .r𝑅 ) 𝑦 ) ∈ V
30 29 elint2 ( ( 𝑥 ( .r𝑅 ) 𝑦 ) ∈ 𝑆 ↔ ∀ 𝑟𝑆 ( 𝑥 ( .r𝑅 ) 𝑦 ) ∈ 𝑟 )
31 28 30 sylibr ( ( ( 𝑆 ⊆ ( SubRing ‘ 𝑅 ) ∧ 𝑆 ≠ ∅ ) ∧ ( 𝑥 𝑆𝑦 𝑆 ) ) → ( 𝑥 ( .r𝑅 ) 𝑦 ) ∈ 𝑆 )
32 31 ralrimivva ( ( 𝑆 ⊆ ( SubRing ‘ 𝑅 ) ∧ 𝑆 ≠ ∅ ) → ∀ 𝑥 𝑆𝑦 𝑆 ( 𝑥 ( .r𝑅 ) 𝑦 ) ∈ 𝑆 )
33 ssn0 ( ( 𝑆 ⊆ ( SubRing ‘ 𝑅 ) ∧ 𝑆 ≠ ∅ ) → ( SubRing ‘ 𝑅 ) ≠ ∅ )
34 n0 ( ( SubRing ‘ 𝑅 ) ≠ ∅ ↔ ∃ 𝑟 𝑟 ∈ ( SubRing ‘ 𝑅 ) )
35 subrgrcl ( 𝑟 ∈ ( SubRing ‘ 𝑅 ) → 𝑅 ∈ Ring )
36 35 exlimiv ( ∃ 𝑟 𝑟 ∈ ( SubRing ‘ 𝑅 ) → 𝑅 ∈ Ring )
37 34 36 sylbi ( ( SubRing ‘ 𝑅 ) ≠ ∅ → 𝑅 ∈ Ring )
38 eqid ( Base ‘ 𝑅 ) = ( Base ‘ 𝑅 )
39 38 9 25 issubrg2 ( 𝑅 ∈ Ring → ( 𝑆 ∈ ( SubRing ‘ 𝑅 ) ↔ ( 𝑆 ∈ ( SubGrp ‘ 𝑅 ) ∧ ( 1r𝑅 ) ∈ 𝑆 ∧ ∀ 𝑥 𝑆𝑦 𝑆 ( 𝑥 ( .r𝑅 ) 𝑦 ) ∈ 𝑆 ) ) )
40 33 37 39 3syl ( ( 𝑆 ⊆ ( SubRing ‘ 𝑅 ) ∧ 𝑆 ≠ ∅ ) → ( 𝑆 ∈ ( SubRing ‘ 𝑅 ) ↔ ( 𝑆 ∈ ( SubGrp ‘ 𝑅 ) ∧ ( 1r𝑅 ) ∈ 𝑆 ∧ ∀ 𝑥 𝑆𝑦 𝑆 ( 𝑥 ( .r𝑅 ) 𝑦 ) ∈ 𝑆 ) ) )
41 6 15 32 40 mpbir3and ( ( 𝑆 ⊆ ( SubRing ‘ 𝑅 ) ∧ 𝑆 ≠ ∅ ) → 𝑆 ∈ ( SubRing ‘ 𝑅 ) )