Nuprl Lemma : remove-repeats-filter
∀[T:Type]. ∀[eq:EqDecider(T)]. ∀[P:T ⟶ 𝔹]. ∀[L:T List].
  (remove-repeats(eq;filter(P;L)) = filter(P;remove-repeats(eq;L)) ∈ (T List))
Proof
Definitions occuring in Statement : 
remove-repeats: remove-repeats(eq;L)
, 
filter: filter(P;l)
, 
list: T List
, 
deq: EqDecider(T)
, 
bool: 𝔹
, 
uall: ∀[x:A]. B[x]
, 
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]
, 
subtype_rel: A ⊆r B
, 
so_apply: x[s]
, 
prop: ℙ
, 
uimplies: b supposing a
, 
all: ∀x:A. B[x]
, 
implies: P 
⇒ Q
, 
top: Top
, 
bool: 𝔹
, 
unit: Unit
, 
it: ⋅
, 
btrue: tt
, 
uiff: uiff(P;Q)
, 
and: P ∧ Q
, 
ifthenelse: if b then t else f fi 
, 
squash: ↓T
, 
true: True
, 
bfalse: ff
, 
exists: ∃x:A. B[x]
, 
or: P ∨ Q
, 
sq_type: SQType(T)
, 
guard: {T}
, 
bnot: ¬bb
, 
assert: ↑b
, 
false: False
, 
deq: EqDecider(T)
, 
iff: P 
⇐⇒ Q
, 
rev_implies: P 
⇐ Q
, 
not: ¬A
, 
eqof: eqof(d)
, 
band: p ∧b q
Lemmas referenced : 
list_induction, 
equal_wf, 
list_wf, 
remove-repeats_wf, 
filter_wf5, 
subtype_rel_dep_function, 
bool_wf, 
l_member_wf, 
set_wf, 
subtype_rel_self, 
filter_nil_lemma, 
remove_repeats_nil_lemma, 
nil_wf, 
filter_cons_lemma, 
remove_repeats_cons_lemma, 
eqtt_to_assert, 
cons_wf, 
eqff_to_assert, 
bool_cases_sqequal, 
subtype_base_sq, 
bool_subtype_base, 
assert-bnot, 
filter-filter, 
band_wf, 
bnot_wf, 
iff_weakening_equal, 
iff_imp_equal_bool, 
assert_elim, 
and_wf, 
not_assert_elim, 
btrue_neq_bfalse, 
assert_wf, 
not_wf, 
iff_transitivity, 
eqof_wf, 
iff_weakening_uiff, 
assert_of_band, 
assert_of_bnot, 
safe-assert-deq, 
iff_wf, 
deq_wf, 
band_commutes
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation, 
introduction, 
cut, 
thin, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
hypothesisEquality, 
sqequalRule, 
lambdaEquality, 
cumulativity, 
hypothesis, 
because_Cache, 
applyEquality, 
setEquality, 
independent_isectElimination, 
setElimination, 
rename, 
lambdaFormation, 
independent_functionElimination, 
dependent_functionElimination, 
isect_memberEquality, 
voidElimination, 
voidEquality, 
functionExtensionality, 
unionElimination, 
equalityElimination, 
equalityTransitivity, 
equalitySymmetry, 
productElimination, 
imageElimination, 
natural_numberEquality, 
imageMemberEquality, 
baseClosed, 
dependent_pairFormation, 
promote_hyp, 
instantiate, 
independent_pairFormation, 
addLevel, 
levelHypothesis, 
dependent_set_memberEquality, 
applyLambdaEquality, 
productEquality, 
impliesFunctionality, 
andLevelFunctionality, 
impliesLevelFunctionality, 
axiomEquality, 
functionEquality, 
universeEquality
Latex:
\mforall{}[T:Type].  \mforall{}[eq:EqDecider(T)].  \mforall{}[P:T  {}\mrightarrow{}  \mBbbB{}].  \mforall{}[L:T  List].
    (remove-repeats(eq;filter(P;L))  =  filter(P;remove-repeats(eq;L)))
Date html generated:
2017_04_17-AM-09_10_35
Last ObjectModification:
2017_02_27-PM-05_19_19
Theory : decidable!equality
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