Nuprl Lemma : seteq-iff-setsubset
∀a,b:coSet{i:l}.  (seteq(a;b) ⇐⇒ (a ⊆ b) ∧ (b ⊆ a))
Proof
Definitions occuring in Statement : 
setsubset: (a ⊆ b), 
seteq: seteq(s1;s2), 
coSet: coSet{i:l}, 
all: ∀x:A. B[x], 
iff: P ⇐⇒ Q, 
and: P ∧ Q
Definitions unfolded in proof : 
guard: {T}, 
so_apply: x[s], 
rev_implies: P ⇐ Q, 
so_lambda: λ2x.t[x], 
uall: ∀[x:A]. B[x], 
prop: ℙ, 
member: t ∈ T, 
implies: P ⇒ Q, 
and: P ∧ Q, 
iff: P ⇐⇒ Q, 
all: ∀x:A. B[x]
Lemmas referenced : 
setsubset_wf, 
seteq_wf, 
setsubset-iff, 
co-seteq-iff, 
iff_wf, 
coSet_wf, 
all_wf, 
setmem_wf
Rules used in proof : 
andLevelFunctionality, 
independent_functionElimination, 
dependent_functionElimination, 
impliesFunctionality, 
addLevel, 
functionEquality, 
productEquality, 
productElimination, 
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\}.    (seteq(a;b)  \mLeftarrow{}{}\mRightarrow{}  (a  \msubseteq{}  b)  \mwedge{}  (b  \msubseteq{}  a))
Date html generated:
2018_07_29-AM-10_01_24
Last ObjectModification:
2018_07_18-PM-01_30_00
Theory : constructive!set!theory
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