Nuprl Lemma : setmem-intersectionset
∀s,x:coSet{i:l}.  ((∃a:coSet{i:l}. (a ∈ s)) ⇒ ((x ∈ ⋂(s)) ⇐⇒ ∀z:coSet{i:l}. ((z ∈ s) ⇒ (x ∈ z))))
Proof
Definitions occuring in Statement : 
intersectionset: ⋂(s), 
setmem: (x ∈ s), 
coSet: coSet{i:l}, 
all: ∀x:A. B[x], 
exists: ∃x:A. B[x], 
iff: P ⇐⇒ Q, 
implies: P ⇒ Q
Definitions unfolded in proof : 
guard: {T}, 
cand: A c∧ B, 
exists: ∃x:A. B[x], 
rev_implies: P ⇐ Q, 
allsetmem: ∀a∈A.P[a], 
set-predicate: set-predicate{i:l}(s;a.P[a]), 
so_apply: x[s], 
prop: ℙ, 
so_lambda: λ2x.t[x], 
uall: ∀[x:A]. B[x], 
member: t ∈ T, 
and: P ∧ Q, 
iff: P ⇐⇒ Q, 
intersectionset: ⋂(s), 
implies: P ⇒ Q, 
all: ∀x:A. B[x]
Lemmas referenced : 
setmem-unionset, 
seteq_weakening, 
setmem_functionality, 
allsetmem-iff, 
exists_wf, 
all_wf, 
iff_wf, 
sub-set_wf, 
seteq_wf, 
set-item_wf, 
setmem_functionality_1, 
coSet_wf, 
setmem_wf, 
allsetmem_wf, 
unionset_wf, 
setmem-sub-coset
Rules used in proof : 
andLevelFunctionality, 
because_Cache, 
dependent_pairFormation, 
functionEquality, 
productEquality, 
instantiate, 
allLevelFunctionality, 
promote_hyp, 
levelHypothesis, 
allFunctionality, 
independent_functionElimination, 
cumulativity, 
setEquality, 
rename, 
setElimination, 
lambdaEquality, 
sqequalRule, 
hypothesis, 
hypothesisEquality, 
isectElimination, 
dependent_functionElimination, 
extract_by_obid, 
introduction, 
impliesFunctionality, 
independent_pairFormation, 
thin, 
productElimination, 
sqequalHypSubstitution, 
addLevel, 
cut, 
lambdaFormation, 
sqequalReflexivity, 
computationStep, 
sqequalTransitivity, 
sqequalSubstitution
Latex:
\mforall{}s,x:coSet\{i:l\}.    ((\mexists{}a:coSet\{i:l\}.  (a  \mmember{}  s))  {}\mRightarrow{}  ((x  \mmember{}  \mcap{}(s))  \mLeftarrow{}{}\mRightarrow{}  \mforall{}z:coSet\{i:l\}.  ((z  \mmember{}  s)  {}\mRightarrow{}  (x  \mmember{}  z))))
 Date html generated: 
2018_07_29-AM-10_01_02
 Last ObjectModification: 
2018_07_18-PM-02_50_25
Theory : constructive!set!theory
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