Nuprl Lemma : ss-mem-open-or
∀[X:SeparationSpace]. ∀T:Type. ∀F:T ⟶ Open(X). ∀x:Point(X).  (x ∈ ⋃t:T.F[t] ⇐⇒ ∃t:T. x ∈ F[t])
Proof
Definitions occuring in Statement : 
ss-open-or: ⋃x:T.F[x], 
ss-mem-open: x ∈ O, 
ss-open: Open(X), 
ss-point: Point(ss), 
separation-space: SeparationSpace, 
uall: ∀[x:A]. B[x], 
so_apply: x[s], 
all: ∀x:A. B[x], 
exists: ∃x:A. B[x], 
iff: P ⇐⇒ Q, 
function: x:A ⟶ B[x], 
universe: Type
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x], 
all: ∀x:A. B[x], 
iff: P ⇐⇒ Q, 
and: P ∧ Q, 
implies: P ⇒ Q, 
ss-open-or: ⋃x:T.F[x], 
ss-mem-open: x ∈ O, 
exists: ∃x:A. B[x], 
member: t ∈ T, 
prop: ℙ, 
so_apply: x[s], 
subtype_rel: A ⊆r B, 
ss-open: Open(X), 
so_lambda: λ2x.t[x], 
rev_implies: P ⇐ Q, 
cand: A c∧ B
Lemmas referenced : 
subtype_rel_self, 
ss-basic_wf, 
ss-mem-basic_wf, 
exists_wf, 
ss-mem-open_wf, 
ss-open-or_wf, 
ss-point_wf, 
ss-open_wf, 
separation-space_wf
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation, 
lambdaFormation, 
independent_pairFormation, 
sqequalHypSubstitution, 
sqequalRule, 
productElimination, 
thin, 
dependent_pairFormation, 
hypothesisEquality, 
hypothesis, 
productEquality, 
cut, 
applyEquality, 
instantiate, 
introduction, 
extract_by_obid, 
isectElimination, 
functionEquality, 
cumulativity, 
universeEquality, 
lambdaEquality, 
because_Cache
Latex:
\mforall{}[X:SeparationSpace].  \mforall{}T:Type.  \mforall{}F:T  {}\mrightarrow{}  Open(X).  \mforall{}x:Point(X).    (x  \mmember{}  \mcup{}t:T.F[t]  \mLeftarrow{}{}\mRightarrow{}  \mexists{}t:T.  x  \mmember{}  F[t])
Date html generated:
2020_05_20-PM-01_22_44
Last ObjectModification:
2018_07_06-PM-05_20_55
Theory : intuitionistic!topology
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