Nuprl Lemma : ss-mem-open-and
∀[X:SeparationSpace]. ∀A,B:Open(X). ∀x:Point(X).  (x ∈ A ⋂ B 
⇐⇒ x ∈ A ∧ x ∈ B)
Proof
Definitions occuring in Statement : 
ss-open-and: A ⋂ B
, 
ss-mem-open: x ∈ O
, 
ss-open: Open(X)
, 
ss-point: Point(ss)
, 
separation-space: SeparationSpace
, 
uall: ∀[x:A]. B[x]
, 
all: ∀x:A. B[x]
, 
iff: P 
⇐⇒ Q
, 
and: P ∧ Q
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-and: A ⋂ B
, 
ss-mem-open: x ∈ O
, 
exists: ∃x:A. B[x]
, 
member: t ∈ T
, 
squash: ↓T
, 
prop: ℙ
, 
true: True
, 
subtype_rel: A ⊆r B
, 
uimplies: b supposing a
, 
guard: {T}
, 
uiff: uiff(P;Q)
, 
ss-open: Open(X)
, 
rev_implies: P 
⇐ Q
, 
cand: A c∧ B
, 
so_lambda: λ2x.t[x]
, 
so_apply: x[s]
, 
rev_uimplies: rev_uimplies(P;Q)
Lemmas referenced : 
ss-mem-basic_wf, 
squash_wf, 
true_wf, 
ss-point_wf, 
ss-basic_wf, 
subtype_rel_self, 
iff_weakening_equal, 
ss-mem-basic-and, 
ss-mem-open_wf, 
ss-open-and_wf, 
ss-basic-and_wf, 
equal_wf, 
exists_wf, 
ss-open_wf, 
separation-space_wf
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation, 
lambdaFormation, 
independent_pairFormation, 
sqequalHypSubstitution, 
sqequalRule, 
productElimination, 
thin, 
cut, 
applyEquality, 
lambdaEquality, 
imageElimination, 
introduction, 
extract_by_obid, 
isectElimination, 
hypothesisEquality, 
equalityTransitivity, 
hypothesis, 
equalitySymmetry, 
because_Cache, 
natural_numberEquality, 
imageMemberEquality, 
baseClosed, 
instantiate, 
universeEquality, 
independent_isectElimination, 
independent_functionElimination, 
dependent_functionElimination, 
dependent_pairFormation, 
productEquality, 
rename
Latex:
\mforall{}[X:SeparationSpace].  \mforall{}A,B:Open(X).  \mforall{}x:Point(X).    (x  \mmember{}  A  \mcap{}  B  \mLeftarrow{}{}\mRightarrow{}  x  \mmember{}  A  \mwedge{}  x  \mmember{}  B)
Date html generated:
2020_05_20-PM-01_22_37
Last ObjectModification:
2018_07_06-PM-04_56_17
Theory : intuitionistic!topology
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