Nuprl Lemma : bag-mapfilter-mapfilter
∀[A,B,C:Type]. ∀[b:bag(A)]. ∀[P:A ⟶ 𝔹]. ∀[f:{x:A| ↑P[x]}  ⟶ B]. ∀[Q:B ⟶ 𝔹]. ∀[g:{x:B| ↑Q[x]}  ⟶ C].
  (bag-mapfilter(g;Q;bag-mapfilter(f;P;b)) = bag-mapfilter(g o f;λx.(P[x] ∧b Q[f[x]]);b) ∈ bag(C))
Proof
Definitions occuring in Statement : 
bag-mapfilter: bag-mapfilter(f;P;bs), 
bag: bag(T), 
compose: f o g, 
band: p ∧b q, 
assert: ↑b, 
bool: 𝔹, 
uall: ∀[x:A]. B[x], 
so_apply: x[s], 
set: {x:A| B[x]} , 
lambda: λx.A[x], 
function: x:A ⟶ B[x], 
universe: Type, 
equal: s = t ∈ T
Definitions unfolded in proof : 
prop: ℙ, 
so_apply: x[s], 
bag-mapfilter: bag-mapfilter(f;P;bs), 
member: t ∈ T, 
uall: ∀[x:A]. B[x], 
so_lambda: λ2x.t[x], 
true: True, 
false: False, 
assert: ↑b, 
bnot: ¬bb, 
guard: {T}, 
sq_type: SQType(T), 
or: P ∨ Q, 
exists: ∃x:A. B[x], 
bfalse: ff, 
ifthenelse: if b then t else f fi , 
band: p ∧b q, 
uimplies: b supposing a, 
and: P ∧ Q, 
uiff: uiff(P;Q), 
btrue: tt, 
it: ⋅, 
unit: Unit, 
bool: 𝔹, 
implies: P ⇒ Q, 
all: ∀x:A. B[x], 
compose: f o g, 
rev_implies: P ⇐ Q, 
iff: P ⇐⇒ Q, 
subtype_rel: A ⊆r B, 
squash: ↓T, 
top: Top, 
decidable: Dec(P), 
not: ¬A
Lemmas referenced : 
bag_wf, 
bool_wf, 
assert_wf, 
istype-universe, 
bag-filter_wf, 
bag-map_wf, 
bfalse_wf, 
assert-bnot, 
bool_subtype_base, 
subtype_base_sq, 
bool_cases_sqequal, 
eqff_to_assert, 
eqtt_to_assert, 
iff_weakening_equal, 
subtype_rel_self, 
bag-filter-map2, 
true_wf, 
squash_wf, 
equal_wf, 
istype-void, 
bag-map-map, 
decidable__assert, 
istype-assert, 
iff_imp_equal_bool, 
btrue_wf, 
istype-true, 
bag-filter-filter2, 
subtype_rel_sets, 
subtype_rel_bag
Rules used in proof : 
universeEquality, 
inhabitedIsType, 
because_Cache, 
axiomEquality, 
isect_memberEquality_alt, 
applyEquality, 
universeIsType, 
hypothesisEquality, 
thin, 
isectElimination, 
sqequalHypSubstitution, 
extract_by_obid, 
setIsType, 
functionIsType, 
hypothesis, 
sqequalRule, 
cut, 
introduction, 
isect_memberFormation_alt, 
sqequalReflexivity, 
computationStep, 
sqequalTransitivity, 
sqequalSubstitution, 
closedConclusion, 
setEquality, 
natural_numberEquality, 
voidElimination, 
independent_functionElimination, 
cumulativity, 
instantiate, 
dependent_functionElimination, 
promote_hyp, 
equalityIsType1, 
dependent_pairFormation_alt, 
dependent_set_memberEquality_alt, 
rename, 
setElimination, 
independent_isectElimination, 
productElimination, 
equalitySymmetry, 
equalityTransitivity, 
equalityElimination, 
unionElimination, 
lambdaFormation_alt, 
lambdaEquality_alt, 
baseClosed, 
imageMemberEquality, 
imageElimination, 
independent_pairFormation, 
applyLambdaEquality, 
hyp_replacement
Latex:
\mforall{}[A,B,C:Type].  \mforall{}[b:bag(A)].  \mforall{}[P:A  {}\mrightarrow{}  \mBbbB{}].  \mforall{}[f:\{x:A|  \muparrow{}P[x]\}    {}\mrightarrow{}  B].  \mforall{}[Q:B  {}\mrightarrow{}  \mBbbB{}].
\mforall{}[g:\{x:B|  \muparrow{}Q[x]\}    {}\mrightarrow{}  C].
    (bag-mapfilter(g;Q;bag-mapfilter(f;P;b))  =  bag-mapfilter(g  o  f;\mlambda{}x.(P[x]  \mwedge{}\msubb{}  Q[f[x]]);b))
Date html generated:
2020_05_20-AM-08_01_36
Last ObjectModification:
2020_01_24-PM-06_25_28
Theory : bags
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