Nuprl Lemma : setsubset-iff
∀a,b:coSet{i:l}.  ((a ⊆ b) ⇐⇒ ∀x:coSet{i:l}. ((x ∈ a) ⇒ (x ∈ b)))
Proof
Definitions occuring in Statement : 
setsubset: (a ⊆ b), 
setmem: (x ∈ s), 
coSet: coSet{i:l}, 
all: ∀x:A. B[x], 
iff: P ⇐⇒ Q, 
implies: P ⇒ Q
Definitions unfolded in proof : 
guard: {T}, 
set-predicate: set-predicate{i:l}(s;a.P[a]), 
rev_implies: P ⇐ Q, 
so_apply: x[s], 
so_lambda: λ2x.t[x], 
uall: ∀[x:A]. B[x], 
prop: ℙ, 
member: t ∈ T, 
implies: P ⇒ Q, 
and: P ∧ Q, 
iff: P ⇐⇒ Q, 
setsubset: (a ⊆ b), 
all: ∀x:A. B[x]
Lemmas referenced : 
iff_wf, 
allsetmem_wf, 
seteq_wf, 
setmem_functionality_1, 
allsetmem-iff, 
coSet_wf, 
all_wf, 
setmem_wf
Rules used in proof : 
independent_functionElimination, 
setEquality, 
rename, 
setElimination, 
dependent_functionElimination, 
impliesFunctionality, 
productElimination, 
addLevel, 
functionEquality, 
cumulativity, 
lambdaEquality, 
sqequalRule, 
instantiate, 
because_Cache, 
hypothesis, 
hypothesisEquality, 
thin, 
isectElimination, 
sqequalHypSubstitution, 
extract_by_obid, 
introduction, 
independent_pairFormation, 
cut, 
lambdaFormation, 
sqequalReflexivity, 
computationStep, 
sqequalTransitivity, 
sqequalSubstitution
Latex:
\mforall{}a,b:coSet\{i:l\}.    ((a  \msubseteq{}  b)  \mLeftarrow{}{}\mRightarrow{}  \mforall{}x:coSet\{i:l\}.  ((x  \mmember{}  a)  {}\mRightarrow{}  (x  \mmember{}  b)))
Date html generated:
2018_07_29-AM-10_01_14
Last ObjectModification:
2018_07_20-PM-06_23_45
Theory : constructive!set!theory
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