Nuprl Lemma : open-isect_wf
∀[X:Type]. ∀[A,B:Open(X)].  (open-isect(A;B) ∈ Open(X))
Proof
Definitions occuring in Statement : 
open-isect: open-isect(A;B)
, 
Open: Open(X)
, 
uall: ∀[x:A]. B[x]
, 
member: t ∈ T
, 
universe: Type
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x]
, 
member: t ∈ T
, 
open-isect: open-isect(A;B)
, 
Open: Open(X)
, 
subtype_rel: A ⊆r B
Lemmas referenced : 
sp-meet_wf, 
Sierpinski_wf, 
Open_wf
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation, 
introduction, 
cut, 
sqequalRule, 
lambdaEquality, 
lemma_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
thin, 
applyEquality, 
hypothesisEquality, 
hypothesis, 
functionEquality, 
axiomEquality, 
equalityTransitivity, 
equalitySymmetry, 
isect_memberEquality, 
because_Cache, 
universeEquality
Latex:
\mforall{}[X:Type].  \mforall{}[A,B:Open(X)].    (open-isect(A;B)  \mmember{}  Open(X))
Date html generated:
2019_10_31-AM-07_18_50
Last ObjectModification:
2015_12_28-AM-11_20_57
Theory : synthetic!topology
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