Nuprl Lemma : bag-combine-com
∀[A,B,C:Type]. ∀[f:A ⟶ B ⟶ bag(C)]. ∀[ba:bag(A)]. ∀[bb:bag(B)].  (⋃a∈ba.⋃b∈bb.f[a;b] = ⋃b∈bb.⋃a∈ba.f[a;b] ∈ bag(C))
Proof
Definitions occuring in Statement : 
bag-combine: ⋃x∈bs.f[x]
, 
bag: bag(T)
, 
uall: ∀[x:A]. B[x]
, 
so_apply: x[s1;s2]
, 
function: x:A ⟶ B[x]
, 
universe: Type
, 
equal: s = t ∈ T
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x]
, 
member: t ∈ T
, 
bag: bag(T)
, 
quotient: x,y:A//B[x; y]
, 
and: P ∧ Q
, 
all: ∀x:A. B[x]
, 
implies: P 
⇒ Q
, 
prop: ℙ
, 
subtype_rel: A ⊆r B
, 
uimplies: b supposing a
, 
so_lambda: λ2x.t[x]
, 
so_apply: x[s1;s2]
, 
so_apply: x[s]
, 
empty-bag: {}
, 
top: Top
, 
bag-append: as + bs
, 
append: as @ bs
, 
so_lambda: so_lambda(x,y,z.t[x; y; z])
, 
so_apply: x[s1;s2;s3]
, 
cand: A c∧ B
, 
true: True
, 
squash: ↓T
, 
guard: {T}
, 
iff: P 
⇐⇒ Q
, 
rev_implies: P 
⇐ Q
, 
so_lambda: λ2x y.t[x; y]
Lemmas referenced : 
bag_wf, 
list_wf, 
permutation_wf, 
equal_wf, 
equal-wf-base, 
bag-combine_wf, 
list-subtype-bag, 
list_induction, 
bag-combine-empty-left, 
bag-combine-empty-right, 
empty-bag_wf, 
list_ind_cons_lemma, 
list_ind_nil_lemma, 
cons_wf, 
nil_wf, 
bag-combine-unit-left, 
bag-combine-append-right, 
bag-append_wf, 
iff_weakening_equal, 
squash_wf, 
true_wf, 
bag-combine-append-left, 
quotient-member-eq, 
permutation-equiv
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation, 
introduction, 
cut, 
sqequalHypSubstitution, 
pointwiseFunctionalityForEquality, 
extract_by_obid, 
isectElimination, 
thin, 
cumulativity, 
hypothesisEquality, 
hypothesis, 
sqequalRule, 
pertypeElimination, 
productElimination, 
equalityTransitivity, 
equalitySymmetry, 
lambdaFormation, 
because_Cache, 
rename, 
dependent_functionElimination, 
independent_functionElimination, 
productEquality, 
isect_memberEquality, 
axiomEquality, 
functionEquality, 
hyp_replacement, 
applyLambdaEquality, 
applyEquality, 
independent_isectElimination, 
lambdaEquality, 
functionExtensionality, 
voidElimination, 
voidEquality, 
independent_pairFormation, 
equalityUniverse, 
levelHypothesis, 
natural_numberEquality, 
imageElimination, 
imageMemberEquality, 
baseClosed, 
universeEquality
Latex:
\mforall{}[A,B,C:Type].  \mforall{}[f:A  {}\mrightarrow{}  B  {}\mrightarrow{}  bag(C)].  \mforall{}[ba:bag(A)].  \mforall{}[bb:bag(B)].
    (\mcup{}a\mmember{}ba.\mcup{}b\mmember{}bb.f[a;b]  =  \mcup{}b\mmember{}bb.\mcup{}a\mmember{}ba.f[a;b])
Date html generated:
2017_10_01-AM-08_47_24
Last ObjectModification:
2017_07_26-PM-04_31_57
Theory : bags
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