Nuprl Lemma : co-regext-loopset
Now we do get ⌜(loopset() ⊆ co-regext(loopset()))⌝, because the type
⌜coW(Unit;x.Unit)⌝ has a single member (while the corresponding W type
⌜W(Unit;x.Unit)⌝ is empty).  So the needed property
⌜∀a:coSet{i:l}. (transitive-set(a) ⇒ (a ⊆ co-regext(a)))⌝ could be true??..⋅
seteq(co-regext(loopset());loopset())
Proof
Definitions occuring in Statement : 
co-regext: co-regext(a), 
loopset: loopset(), 
seteq: seteq(s1;s2)
Definitions unfolded in proof : 
all: ∀x:A. B[x], 
uall: ∀[x:A]. B[x], 
member: t ∈ T, 
so_lambda: λ2x.t[x], 
so_apply: x[s], 
loopset: loopset(), 
set-dom: set-dom(s), 
pi1: fst(t), 
guard: {T}, 
implies: P ⇒ Q, 
and: P ∧ Q, 
uimplies: b supposing a, 
respects-equality: respects-equality(S;T), 
subtype_rel: A ⊆r B, 
regextfun: regextfun(f;w), 
mk-coset: mk-coset(T;f), 
mk-set: f"(T), 
Wsup: Wsup(a;b), 
ext-eq: A ≡ B, 
unit: Unit, 
prop: ℙ, 
so_apply: x[s1;s2], 
F-bisimulation: x,y.R[x; y] is an T.F[T]-bisimulation, 
true: True, 
squash: ↓T, 
exists: ∃x:A. B[x], 
top: Top, 
rev_implies: P ⇐ Q, 
iff: P ⇐⇒ Q, 
co-regext: co-regext(a)
Lemmas referenced : 
regextfun_wf, 
unit_wf2, 
loopset_wf, 
coW_wf, 
coSet-equality2, 
subtype_rel_wf, 
coSet_wf, 
istype-universe, 
subtype-respects-equality, 
loopset-sq, 
coW-ext, 
subtype_rel_weakening, 
equal-wf-base, 
set-dom_wf, 
coW-corec, 
ext-eq_inversion, 
corec_wf, 
coinduction-principle, 
continuous-monotone-product, 
continuous-monotone-constant, 
continuous-monotone-function, 
continuous-monotone-id, 
true_wf, 
istype-true, 
corec-ext, 
equal-unit, 
subtype_rel_self, 
iff_wf, 
all_wf, 
setmem-loopset, 
exists_wf, 
setmem_wf, 
iff_weakening_equal, 
squash_wf, 
seteq_wf, 
setmem-mk-coset, 
co-regext_wf, 
co-seteq-iff, 
fix_wf_coW, 
it_wf, 
fix_wf_corec
Rules used in proof : 
cut, 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
lambdaFormation, 
introduction, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
thin, 
hypothesis, 
lambdaEquality, 
sqequalRule, 
hypothesisEquality, 
lambdaFormation_alt, 
universeIsType, 
lambdaEquality_alt, 
dependent_functionElimination, 
independent_functionElimination, 
productIsType, 
instantiate, 
productEquality, 
universeEquality, 
functionEquality, 
cumulativity, 
productElimination, 
equalityIstype, 
baseClosed, 
independent_isectElimination, 
sqequalBase, 
equalitySymmetry, 
hypothesis_subsumption, 
applyEquality, 
because_Cache, 
inhabitedIsType, 
dependent_pairEquality_alt, 
functionIsType, 
intEquality, 
equalityTransitivity, 
promote_hyp, 
natural_numberEquality, 
functionExtensionality_alt, 
applyLambdaEquality, 
impliesFunctionality, 
allFunctionality, 
addLevel, 
imageMemberEquality, 
imageElimination, 
voidEquality, 
voidElimination, 
isect_memberEquality, 
independent_pairFormation, 
dependent_pairEquality, 
rename, 
dependent_pairFormation
Latex:
seteq(co-regext(loopset());loopset())
 Date html generated: 
2020_05_20-PM-01_19_29
 Last ObjectModification: 
2019_12_10-AM-11_33_32
Theory : constructive!set!theory
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