Nuprl Lemma : bag-combine-combine
∀[A,B,C:Type]. ∀[b:bag(A)]. ∀[f:A ⟶ bag(B)]. ∀[g:B ⟶ bag(C)].  (⋃x∈⋃y∈b.f[y].g[x] = ⋃x∈b.⋃y∈f[x].g[y] ∈ bag(C))
Proof
Definitions occuring in Statement : 
bag-combine: ⋃x∈bs.f[x]
, 
bag: bag(T)
, 
uall: ∀[x:A]. B[x]
, 
so_apply: x[s]
, 
function: x:A ⟶ B[x]
, 
universe: Type
, 
equal: s = t ∈ T
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x]
, 
member: t ∈ T
, 
so_lambda: λ2x.t[x]
, 
top: Top
, 
so_apply: x[s]
, 
subtype_rel: A ⊆r B
, 
uimplies: b supposing a
Lemmas referenced : 
bag-combine-assoc, 
subtype_rel_bag, 
top_wf, 
trivial-equal, 
bag_wf, 
bag-combine_wf
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation, 
introduction, 
cut, 
equalitySymmetry, 
sqequalRule, 
lemma_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
thin, 
isect_memberEquality, 
voidElimination, 
voidEquality, 
hypothesisEquality, 
applyEquality, 
hypothesis, 
independent_isectElimination, 
lambdaEquality, 
because_Cache, 
functionEquality, 
axiomEquality
Latex:
\mforall{}[A,B,C:Type].  \mforall{}[b:bag(A)].  \mforall{}[f:A  {}\mrightarrow{}  bag(B)].  \mforall{}[g:B  {}\mrightarrow{}  bag(C)].
    (\mcup{}x\mmember{}\mcup{}y\mmember{}b.f[y].g[x]  =  \mcup{}x\mmember{}b.\mcup{}y\mmember{}f[x].g[y])
Date html generated:
2016_05_15-PM-02_29_08
Last ObjectModification:
2015_12_27-AM-09_49_51
Theory : bags
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