Nuprl Lemma : member-filter
∀[T:Type]. ∀P:T ⟶ 𝔹. ∀L:T List. ∀x:{x:T| ↑P[x]} .  ((x ∈ filter(λx.P[x];L)) 
⇐⇒ (x ∈ L))
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]
, 
all: ∀x:A. B[x]
, 
iff: P 
⇐⇒ Q
, 
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]
, 
all: ∀x:A. B[x]
, 
member: t ∈ T
, 
so_lambda: λ2x.t[x]
, 
prop: ℙ
, 
so_apply: x[s]
, 
implies: P 
⇒ Q
, 
iff: P 
⇐⇒ Q
, 
and: P ∧ Q
, 
uimplies: b supposing a
, 
not: ¬A
, 
false: False
, 
rev_implies: P 
⇐ Q
, 
bool: 𝔹
, 
unit: Unit
, 
it: ⋅
, 
btrue: tt
, 
uiff: uiff(P;Q)
, 
ifthenelse: if b then t else f fi 
, 
bfalse: ff
, 
exists: ∃x:A. B[x]
, 
or: P ∨ Q
, 
sq_type: SQType(T)
, 
guard: {T}
, 
bnot: ¬bb
, 
assert: ↑b
, 
squash: ↓T
, 
true: True
Lemmas referenced : 
list_induction, 
assert_wf, 
iff_wf, 
l_member_wf, 
filter_type, 
list_wf, 
filter_nil_lemma, 
null_nil_lemma, 
btrue_wf, 
member-implies-null-eq-bfalse, 
nil_wf, 
istype-assert, 
btrue_neq_bfalse, 
filter_cons_lemma, 
eqtt_to_assert, 
eqff_to_assert, 
bool_cases_sqequal, 
subtype_base_sq, 
bool_wf, 
bool_subtype_base, 
assert-bnot, 
istype-universe, 
equal_functionality_wrt_subtype_rel2, 
subtype_rel_set_simple, 
cons_member, 
cons_wf, 
assert_elim, 
equal_wf, 
and_wf, 
not_assert_elim, 
or_wf
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation_alt, 
lambdaFormation_alt, 
cut, 
thin, 
introduction, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
hypothesisEquality, 
sqequalRule, 
lambdaEquality_alt, 
functionEquality, 
setEquality, 
applyEquality, 
hypothesis, 
universeIsType, 
setElimination, 
rename, 
independent_functionElimination, 
dependent_functionElimination, 
Error :memTop, 
independent_pairFormation, 
dependent_set_memberEquality_alt, 
independent_isectElimination, 
equalityTransitivity, 
equalitySymmetry, 
voidElimination, 
because_Cache, 
setIsType, 
inhabitedIsType, 
unionElimination, 
equalityElimination, 
productElimination, 
dependent_pairFormation_alt, 
equalityIstype, 
promote_hyp, 
instantiate, 
cumulativity, 
functionIsType, 
productIsType, 
universeEquality, 
inlFormation_alt, 
inrFormation_alt, 
unionIsType, 
applyLambdaEquality, 
imageMemberEquality, 
baseClosed, 
imageElimination, 
inlFormation, 
natural_numberEquality, 
dependent_set_memberEquality, 
inrFormation, 
lambdaFormation, 
lambdaEquality
Latex:
\mforall{}[T:Type].  \mforall{}P:T  {}\mrightarrow{}  \mBbbB{}.  \mforall{}L:T  List.  \mforall{}x:\{x:T|  \muparrow{}P[x]\}  .    ((x  \mmember{}  filter(\mlambda{}x.P[x];L))  \mLeftarrow{}{}\mRightarrow{}  (x  \mmember{}  L))
Date html generated:
2020_05_19-PM-09_37_46
Last ObjectModification:
2020_01_04-PM-07_57_53
Theory : list_0
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