Nuprl Lemma : filter_wf4
∀[T:Type]. ∀[P:T ⟶ 𝔹]. ∀[l:T List].  (filter(λx.P[x];l) ∈ {x:T| (x ∈ l) ∧ (↑P[x])}  List)
Proof
Definitions occuring in Statement : 
l_member: (x ∈ l), 
filter: filter(P;l), 
list: T List, 
assert: ↑b, 
bool: 𝔹, 
uall: ∀[x:A]. B[x], 
so_apply: x[s], 
and: P ∧ Q, 
member: t ∈ T, 
set: {x:A| B[x]} , 
lambda: λx.A[x], 
function: x:A ⟶ B[x], 
universe: Type
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x], 
member: t ∈ T, 
all: ∀x:A. B[x], 
nat: ℕ, 
implies: P ⇒ Q, 
false: False, 
ge: i ≥ j , 
guard: {T}, 
uimplies: b supposing a, 
prop: ℙ, 
subtype_rel: A ⊆r B, 
or: P ∨ Q, 
top: Top, 
and: P ∧ Q, 
so_apply: x[s], 
cons: [a / b], 
colength: colength(L), 
so_lambda: λ2x y.t[x; y], 
so_apply: x[s1;s2], 
squash: ↓T, 
sq_stable: SqStable(P), 
uiff: uiff(P;Q), 
le: A ≤ B, 
not: ¬A, 
less_than': less_than'(a;b), 
true: True, 
decidable: Dec(P), 
iff: P ⇐⇒ Q, 
rev_implies: P ⇐ Q, 
subtract: n - m, 
nil: [], 
it: ⋅, 
so_lambda: λ2x.t[x], 
sq_type: SQType(T), 
less_than: a < b, 
bool: 𝔹, 
unit: Unit, 
btrue: tt, 
ifthenelse: if b then t else f fi , 
cand: A c∧ B, 
bfalse: ff, 
exists: ∃x:A. B[x], 
bnot: ¬bb, 
assert: ↑b
Lemmas referenced : 
nat_properties, 
less_than_transitivity1, 
less_than_irreflexivity, 
ge_wf, 
less_than_wf, 
equal-wf-T-base, 
nat_wf, 
colength_wf_list, 
list-cases, 
filter_nil_lemma, 
nil_wf, 
l_member_wf, 
assert_wf, 
product_subtype_list, 
spread_cons_lemma, 
sq_stable__le, 
le_antisymmetry_iff, 
add_functionality_wrt_le, 
add-associates, 
add-zero, 
zero-add, 
le-add-cancel, 
decidable__le, 
false_wf, 
not-le-2, 
condition-implies-le, 
minus-add, 
minus-one-mul, 
minus-one-mul-top, 
add-commutes, 
le_wf, 
equal_wf, 
subtract_wf, 
not-ge-2, 
less-iff-le, 
minus-minus, 
add-swap, 
subtype_base_sq, 
set_subtype_base, 
int_subtype_base, 
filter_cons_lemma, 
bool_wf, 
eqtt_to_assert, 
cons_wf, 
cons_member, 
subtype_rel_list_set, 
eqff_to_assert, 
bool_cases_sqequal, 
bool_subtype_base, 
assert-bnot, 
list_wf
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation, 
introduction, 
cut, 
thin, 
lambdaFormation, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
hypothesisEquality, 
hypothesis, 
setElimination, 
rename, 
sqequalRule, 
intWeakElimination, 
natural_numberEquality, 
independent_isectElimination, 
independent_functionElimination, 
voidElimination, 
lambdaEquality, 
dependent_functionElimination, 
axiomEquality, 
equalityTransitivity, 
equalitySymmetry, 
cumulativity, 
applyEquality, 
because_Cache, 
unionElimination, 
isect_memberEquality, 
voidEquality, 
setEquality, 
productEquality, 
functionExtensionality, 
promote_hyp, 
hypothesis_subsumption, 
productElimination, 
applyLambdaEquality, 
imageMemberEquality, 
baseClosed, 
imageElimination, 
addEquality, 
dependent_set_memberEquality, 
independent_pairFormation, 
minusEquality, 
intEquality, 
instantiate, 
equalityElimination, 
inlFormation, 
inrFormation, 
dependent_pairFormation, 
functionEquality, 
universeEquality
Latex:
\mforall{}[T:Type].  \mforall{}[P:T  {}\mrightarrow{}  \mBbbB{}].  \mforall{}[l:T  List].    (filter(\mlambda{}x.P[x];l)  \mmember{}  \{x:T|  (x  \mmember{}  l)  \mwedge{}  (\muparrow{}P[x])\}    List)
Date html generated:
2017_04_14-AM-08_51_49
Last ObjectModification:
2017_02_27-PM-03_37_34
Theory : list_0
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