Nuprl Lemma : bag-from-member-function-exists
∀[T,A:Type].
  ∀bs:bag(T). ∀P:T ⟶ A ⟶ ℙ.
    ((∀x,y:A.  Dec(x = y ∈ A))
    ⇒ (∀x,y:T.  Dec(x = y ∈ T))
    ⇒ (∀i:T. (i ↓∈ bs ⇒ (∃a:A. P[i;a])))
    ⇒ (∃b:bag(T × A). ((∀i:T. (i ↓∈ bs ⇒ i ↓∈ bag-map(λx.(fst(x));b))) ∧ (∀x:T × A. (x ↓∈ b ⇒ P[fst(x);snd(x)])))))
Proof
Definitions occuring in Statement : 
bag-member: x ↓∈ bs, 
bag-map: bag-map(f;bs), 
bag: bag(T), 
decidable: Dec(P), 
uall: ∀[x:A]. B[x], 
prop: ℙ, 
so_apply: x[s1;s2], 
pi1: fst(t), 
pi2: snd(t), 
all: ∀x:A. B[x], 
exists: ∃x:A. B[x], 
implies: P ⇒ Q, 
and: P ∧ Q, 
lambda: λx.A[x], 
function: x:A ⟶ B[x], 
product: x:A × B[x], 
universe: Type, 
equal: s = t ∈ T
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x], 
all: ∀x:A. B[x], 
implies: P ⇒ Q, 
exists: ∃x:A. B[x], 
member: t ∈ T, 
prop: ℙ, 
so_lambda: λ2x.t[x], 
so_apply: x[s1;s2], 
subtype_rel: A ⊆r B, 
so_apply: x[s], 
uimplies: b supposing a, 
and: P ∧ Q, 
uiff: uiff(P;Q), 
rev_uimplies: rev_uimplies(P;Q), 
bag-member: x ↓∈ bs, 
squash: ↓T, 
pi1: fst(t), 
inject: Inj(A;B;f), 
sq_stable: SqStable(P), 
respects-equality: respects-equality(S;T), 
true: True, 
guard: {T}, 
iff: P ⇐⇒ Q, 
rev_implies: P ⇐ Q, 
pi2: snd(t)
Lemmas referenced : 
bag-map-member-wf, 
bag-member_wf, 
pi1_wf, 
bag-member-evidence, 
subtype_rel_self, 
bag-map_wf, 
pi2_wf, 
decidable_wf, 
equal_wf, 
bag_wf, 
istype-universe, 
bag-member-map2, 
bag-member-map3-deq, 
sq_stable__bag-member, 
respects-equality-product, 
respects-equality-set-trivial2, 
respects-equality-trivial, 
istype-base, 
decidable__equal_product, 
squash_wf, 
true_wf, 
iff_weakening_equal
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation_alt, 
lambdaFormation_alt, 
rename, 
dependent_pairFormation_alt, 
cut, 
introduction, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
thin, 
hypothesisEquality, 
productEquality, 
lambdaEquality_alt, 
hypothesis, 
universeIsType, 
setElimination, 
independent_pairEquality, 
because_Cache, 
sqequalRule, 
applyEquality, 
independent_isectElimination, 
setIsType, 
productIsType, 
functionIsType, 
inhabitedIsType, 
instantiate, 
universeEquality, 
independent_pairFormation, 
dependent_functionElimination, 
setEquality, 
productElimination, 
imageElimination, 
imageMemberEquality, 
baseClosed, 
dependent_set_memberEquality_alt, 
equalityIsType1, 
independent_functionElimination, 
equalitySymmetry, 
equalityTransitivity, 
equalityIstype, 
applyLambdaEquality, 
sqequalBase, 
functionEquality, 
cumulativity, 
natural_numberEquality
Latex:
\mforall{}[T,A:Type].
    \mforall{}bs:bag(T).  \mforall{}P:T  {}\mrightarrow{}  A  {}\mrightarrow{}  \mBbbP{}.
        ((\mforall{}x,y:A.    Dec(x  =  y))
        {}\mRightarrow{}  (\mforall{}x,y:T.    Dec(x  =  y))
        {}\mRightarrow{}  (\mforall{}i:T.  (i  \mdownarrow{}\mmember{}  bs  {}\mRightarrow{}  (\mexists{}a:A.  P[i;a])))
        {}\mRightarrow{}  (\mexists{}b:bag(T  \mtimes{}  A)
                  ((\mforall{}i:T.  (i  \mdownarrow{}\mmember{}  bs  {}\mRightarrow{}  i  \mdownarrow{}\mmember{}  bag-map(\mlambda{}x.(fst(x));b)))
                  \mwedge{}  (\mforall{}x:T  \mtimes{}  A.  (x  \mdownarrow{}\mmember{}  b  {}\mRightarrow{}  P[fst(x);snd(x)])))))
Date html generated:
2019_10_15-AM-11_04_05
Last ObjectModification:
2019_06_25-PM-01_21_12
Theory : bags
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