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Database
BASIC TOPOLOGY
Filters and filter bases
Filter limits
flimneiss
Metamath Proof Explorer
Description: A filter contains the neighborhood filter as a subfilter. (Contributed by Mario Carneiro , 9-Apr-2015) (Revised by Stefan O'Rear , 9-Aug-2015)
Ref
Expression
Assertion
flimneiss
⊢ A ∈ J fLim F → nei ⁡ J ⁡ A ⊆ F
Proof
Step
Hyp
Ref
Expression
1
eqid
⊢ ⋃ J = ⋃ J
2
1
elflim2
⊢ A ∈ J fLim F ↔ J ∈ Top ∧ F ∈ ⋃ ran ⁡ Fil ∧ F ⊆ 𝒫 ⋃ J ∧ A ∈ ⋃ J ∧ nei ⁡ J ⁡ A ⊆ F
3
2
simprbi
⊢ A ∈ J fLim F → A ∈ ⋃ J ∧ nei ⁡ J ⁡ A ⊆ F
4
3
simprd
⊢ A ∈ J fLim F → nei ⁡ J ⁡ A ⊆ F