Nuprl Lemma : ss-open-and_wf
∀[X:SeparationSpace]. ∀[A,B:Open(X)].  (A ⋂ B ∈ Open(X))
Proof
Definitions occuring in Statement : 
ss-open-and: A ⋂ B
, 
ss-open: Open(X)
, 
separation-space: SeparationSpace
, 
uall: ∀[x:A]. B[x]
, 
member: t ∈ T
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x]
, 
member: t ∈ T
, 
ss-open-and: A ⋂ B
, 
so_lambda: λ2x.t[x]
, 
prop: ℙ
, 
and: P ∧ Q
, 
ss-open: Open(X)
, 
subtype_rel: A ⊆r B
, 
so_apply: x[s]
Lemmas referenced : 
exists_wf, 
ss-basic_wf, 
subtype_rel_self, 
equal_wf, 
ss-basic-and_wf, 
ss-open_wf, 
separation-space_wf
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation, 
introduction, 
cut, 
sqequalRule, 
lambdaEquality, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
thin, 
hypothesisEquality, 
hypothesis, 
productEquality, 
applyEquality, 
instantiate, 
universeEquality, 
because_Cache, 
axiomEquality, 
equalityTransitivity, 
equalitySymmetry, 
isect_memberEquality
Latex:
\mforall{}[X:SeparationSpace].  \mforall{}[A,B:Open(X)].    (A  \mcap{}  B  \mmember{}  Open(X))
Date html generated:
2020_05_20-PM-01_22_35
Last ObjectModification:
2018_07_06-PM-04_49_20
Theory : intuitionistic!topology
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