Metamath Proof Explorer


Theorem ntrneix2

Description: An interior (closure) function is expansive if and only if all subsets which contain a point are neighborhoods (convergents) of that point. (Contributed by RP, 11-Jun-2021)

Ref Expression
Hypotheses ntrnei.o 𝑂 = ( 𝑖 ∈ V , 𝑗 ∈ V ↦ ( 𝑘 ∈ ( 𝒫 𝑗m 𝑖 ) ↦ ( 𝑙𝑗 ↦ { 𝑚𝑖𝑙 ∈ ( 𝑘𝑚 ) } ) ) )
ntrnei.f 𝐹 = ( 𝒫 𝐵 𝑂 𝐵 )
ntrnei.r ( 𝜑𝐼 𝐹 𝑁 )
Assertion ntrneix2 ( 𝜑 → ( ∀ 𝑠 ∈ 𝒫 𝐵 𝑠 ⊆ ( 𝐼𝑠 ) ↔ ∀ 𝑥𝐵𝑠 ∈ 𝒫 𝐵 ( 𝑥𝑠𝑠 ∈ ( 𝑁𝑥 ) ) ) )

Proof

Step Hyp Ref Expression
1 ntrnei.o 𝑂 = ( 𝑖 ∈ V , 𝑗 ∈ V ↦ ( 𝑘 ∈ ( 𝒫 𝑗m 𝑖 ) ↦ ( 𝑙𝑗 ↦ { 𝑚𝑖𝑙 ∈ ( 𝑘𝑚 ) } ) ) )
2 ntrnei.f 𝐹 = ( 𝒫 𝐵 𝑂 𝐵 )
3 ntrnei.r ( 𝜑𝐼 𝐹 𝑁 )
4 simpr ( ( 𝜑𝑠 ∈ 𝒫 𝐵 ) → 𝑠 ∈ 𝒫 𝐵 )
5 elpwi ( 𝑠 ∈ 𝒫 𝐵𝑠𝐵 )
6 5 sselda ( ( 𝑠 ∈ 𝒫 𝐵𝑥𝑠 ) → 𝑥𝐵 )
7 biimt ( 𝑥𝐵 → ( 𝑥 ∈ ( 𝐼𝑠 ) ↔ ( 𝑥𝐵𝑥 ∈ ( 𝐼𝑠 ) ) ) )
8 6 7 syl ( ( 𝑠 ∈ 𝒫 𝐵𝑥𝑠 ) → ( 𝑥 ∈ ( 𝐼𝑠 ) ↔ ( 𝑥𝐵𝑥 ∈ ( 𝐼𝑠 ) ) ) )
9 8 pm5.74da ( 𝑠 ∈ 𝒫 𝐵 → ( ( 𝑥𝑠𝑥 ∈ ( 𝐼𝑠 ) ) ↔ ( 𝑥𝑠 → ( 𝑥𝐵𝑥 ∈ ( 𝐼𝑠 ) ) ) ) )
10 bi2.04 ( ( 𝑥𝑠 → ( 𝑥𝐵𝑥 ∈ ( 𝐼𝑠 ) ) ) ↔ ( 𝑥𝐵 → ( 𝑥𝑠𝑥 ∈ ( 𝐼𝑠 ) ) ) )
11 9 10 bitrdi ( 𝑠 ∈ 𝒫 𝐵 → ( ( 𝑥𝑠𝑥 ∈ ( 𝐼𝑠 ) ) ↔ ( 𝑥𝐵 → ( 𝑥𝑠𝑥 ∈ ( 𝐼𝑠 ) ) ) ) )
12 11 albidv ( 𝑠 ∈ 𝒫 𝐵 → ( ∀ 𝑥 ( 𝑥𝑠𝑥 ∈ ( 𝐼𝑠 ) ) ↔ ∀ 𝑥 ( 𝑥𝐵 → ( 𝑥𝑠𝑥 ∈ ( 𝐼𝑠 ) ) ) ) )
13 dfss2 ( 𝑠 ⊆ ( 𝐼𝑠 ) ↔ ∀ 𝑥 ( 𝑥𝑠𝑥 ∈ ( 𝐼𝑠 ) ) )
14 df-ral ( ∀ 𝑥𝐵 ( 𝑥𝑠𝑥 ∈ ( 𝐼𝑠 ) ) ↔ ∀ 𝑥 ( 𝑥𝐵 → ( 𝑥𝑠𝑥 ∈ ( 𝐼𝑠 ) ) ) )
15 12 13 14 3bitr4g ( 𝑠 ∈ 𝒫 𝐵 → ( 𝑠 ⊆ ( 𝐼𝑠 ) ↔ ∀ 𝑥𝐵 ( 𝑥𝑠𝑥 ∈ ( 𝐼𝑠 ) ) ) )
16 4 15 syl ( ( 𝜑𝑠 ∈ 𝒫 𝐵 ) → ( 𝑠 ⊆ ( 𝐼𝑠 ) ↔ ∀ 𝑥𝐵 ( 𝑥𝑠𝑥 ∈ ( 𝐼𝑠 ) ) ) )
17 3 ad2antrr ( ( ( 𝜑𝑠 ∈ 𝒫 𝐵 ) ∧ 𝑥𝐵 ) → 𝐼 𝐹 𝑁 )
18 simpr ( ( ( 𝜑𝑠 ∈ 𝒫 𝐵 ) ∧ 𝑥𝐵 ) → 𝑥𝐵 )
19 simplr ( ( ( 𝜑𝑠 ∈ 𝒫 𝐵 ) ∧ 𝑥𝐵 ) → 𝑠 ∈ 𝒫 𝐵 )
20 1 2 17 18 19 ntrneiel ( ( ( 𝜑𝑠 ∈ 𝒫 𝐵 ) ∧ 𝑥𝐵 ) → ( 𝑥 ∈ ( 𝐼𝑠 ) ↔ 𝑠 ∈ ( 𝑁𝑥 ) ) )
21 20 imbi2d ( ( ( 𝜑𝑠 ∈ 𝒫 𝐵 ) ∧ 𝑥𝐵 ) → ( ( 𝑥𝑠𝑥 ∈ ( 𝐼𝑠 ) ) ↔ ( 𝑥𝑠𝑠 ∈ ( 𝑁𝑥 ) ) ) )
22 21 ralbidva ( ( 𝜑𝑠 ∈ 𝒫 𝐵 ) → ( ∀ 𝑥𝐵 ( 𝑥𝑠𝑥 ∈ ( 𝐼𝑠 ) ) ↔ ∀ 𝑥𝐵 ( 𝑥𝑠𝑠 ∈ ( 𝑁𝑥 ) ) ) )
23 16 22 bitrd ( ( 𝜑𝑠 ∈ 𝒫 𝐵 ) → ( 𝑠 ⊆ ( 𝐼𝑠 ) ↔ ∀ 𝑥𝐵 ( 𝑥𝑠𝑠 ∈ ( 𝑁𝑥 ) ) ) )
24 23 ralbidva ( 𝜑 → ( ∀ 𝑠 ∈ 𝒫 𝐵 𝑠 ⊆ ( 𝐼𝑠 ) ↔ ∀ 𝑠 ∈ 𝒫 𝐵𝑥𝐵 ( 𝑥𝑠𝑠 ∈ ( 𝑁𝑥 ) ) ) )
25 ralcom ( ∀ 𝑠 ∈ 𝒫 𝐵𝑥𝐵 ( 𝑥𝑠𝑠 ∈ ( 𝑁𝑥 ) ) ↔ ∀ 𝑥𝐵𝑠 ∈ 𝒫 𝐵 ( 𝑥𝑠𝑠 ∈ ( 𝑁𝑥 ) ) )
26 24 25 bitrdi ( 𝜑 → ( ∀ 𝑠 ∈ 𝒫 𝐵 𝑠 ⊆ ( 𝐼𝑠 ) ↔ ∀ 𝑥𝐵𝑠 ∈ 𝒫 𝐵 ( 𝑥𝑠𝑠 ∈ ( 𝑁𝑥 ) ) ) )