Theorem islp3

Description: The predicate " P is a limit point of S " in terms of open sets. see islp2 , elcls , islp . (Contributed by FL, 31-Jul-2009)

	Ref	Expression
Hypothesis	lpfval.1	⊢ 𝑋 = ∪ 𝐽
Assertion	islp3	⊢ ( ( 𝐽 ∈ Top ∧ 𝑆 ⊆ 𝑋 ∧ 𝑃 ∈ 𝑋 ) → ( 𝑃 ∈ ( ( limPt ‘ 𝐽 ) ‘ 𝑆 ) ↔ ∀ 𝑥 ∈ 𝐽 ( 𝑃 ∈ 𝑥 → ( 𝑥 ∩ ( 𝑆 ∖ { 𝑃 } ) ) ≠ ∅ ) ) )

Proof

Step	Hyp	Ref	Expression
1		lpfval.1	⊢ 𝑋 = ∪ 𝐽
2	1	islp	⊢ ( ( 𝐽 ∈ Top ∧ 𝑆 ⊆ 𝑋 ) → ( 𝑃 ∈ ( ( limPt ‘ 𝐽 ) ‘ 𝑆 ) ↔ 𝑃 ∈ ( ( cls ‘ 𝐽 ) ‘ ( 𝑆 ∖ { 𝑃 } ) ) ) )
3	2	3adant3	⊢ ( ( 𝐽 ∈ Top ∧ 𝑆 ⊆ 𝑋 ∧ 𝑃 ∈ 𝑋 ) → ( 𝑃 ∈ ( ( limPt ‘ 𝐽 ) ‘ 𝑆 ) ↔ 𝑃 ∈ ( ( cls ‘ 𝐽 ) ‘ ( 𝑆 ∖ { 𝑃 } ) ) ) )
4		simp2	⊢ ( ( 𝐽 ∈ Top ∧ 𝑆 ⊆ 𝑋 ∧ 𝑃 ∈ 𝑋 ) → 𝑆 ⊆ 𝑋 )
5	4	ssdifssd	⊢ ( ( 𝐽 ∈ Top ∧ 𝑆 ⊆ 𝑋 ∧ 𝑃 ∈ 𝑋 ) → ( 𝑆 ∖ { 𝑃 } ) ⊆ 𝑋 )
6	1	elcls	⊢ ( ( 𝐽 ∈ Top ∧ ( 𝑆 ∖ { 𝑃 } ) ⊆ 𝑋 ∧ 𝑃 ∈ 𝑋 ) → ( 𝑃 ∈ ( ( cls ‘ 𝐽 ) ‘ ( 𝑆 ∖ { 𝑃 } ) ) ↔ ∀ 𝑥 ∈ 𝐽 ( 𝑃 ∈ 𝑥 → ( 𝑥 ∩ ( 𝑆 ∖ { 𝑃 } ) ) ≠ ∅ ) ) )
7	5 6	syld3an2	⊢ ( ( 𝐽 ∈ Top ∧ 𝑆 ⊆ 𝑋 ∧ 𝑃 ∈ 𝑋 ) → ( 𝑃 ∈ ( ( cls ‘ 𝐽 ) ‘ ( 𝑆 ∖ { 𝑃 } ) ) ↔ ∀ 𝑥 ∈ 𝐽 ( 𝑃 ∈ 𝑥 → ( 𝑥 ∩ ( 𝑆 ∖ { 𝑃 } ) ) ≠ ∅ ) ) )
8	3 7	bitrd	⊢ ( ( 𝐽 ∈ Top ∧ 𝑆 ⊆ 𝑋 ∧ 𝑃 ∈ 𝑋 ) → ( 𝑃 ∈ ( ( limPt ‘ 𝐽 ) ‘ 𝑆 ) ↔ ∀ 𝑥 ∈ 𝐽 ( 𝑃 ∈ 𝑥 → ( 𝑥 ∩ ( 𝑆 ∖ { 𝑃 } ) ) ≠ ∅ ) ) )