Nuprl Lemma : length-filter-lower-bound
∀[A:Type]. ∀[P:A ⟶ 𝔹]. ∀[L:A List]. ∀[T:Type]. ∀[k:ℕ]. ∀[f:{i:ℕ||L||| ¬↑P[L[i]]}  ⟶ T].
  ((||L|| - k) ≤ ||filter(P;L)||) supposing (T ~ ℕk and Inj({i:ℕ||L||| ¬↑P[L[i]]} T;f))
Proof
Definitions occuring in Statement : 
equipollent: A ~ B
, 
select: L[n]
, 
length: ||as||
, 
filter: filter(P;l)
, 
list: T List
, 
inject: Inj(A;B;f)
, 
int_seg: {i..j-}
, 
nat: ℕ
, 
assert: ↑b
, 
bool: 𝔹
, 
uimplies: b supposing a
, 
uall: ∀[x:A]. B[x]
, 
so_apply: x[s]
, 
le: A ≤ B
, 
not: ¬A
, 
set: {x:A| B[x]} 
, 
function: x:A ⟶ B[x]
, 
subtract: n - m
, 
natural_number: $n
, 
universe: Type
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x]
, 
member: t ∈ T
, 
uimplies: b supposing a
, 
le: A ≤ B
, 
and: P ∧ Q
, 
nat: ℕ
, 
so_apply: x[s]
, 
int_seg: {i..j-}
, 
guard: {T}
, 
ge: i ≥ j 
, 
lelt: i ≤ j < k
, 
all: ∀x:A. B[x]
, 
decidable: Dec(P)
, 
or: P ∨ Q
, 
not: ¬A
, 
implies: P 
⇒ Q
, 
satisfiable_int_formula: satisfiable_int_formula(fmla)
, 
exists: ∃x:A. B[x]
, 
false: False
, 
top: Top
, 
prop: ℙ
, 
less_than: a < b
, 
squash: ↓T
, 
so_lambda: λ2x.t[x]
, 
cand: A c∧ B
, 
biject: Bij(A;B;f)
, 
equipollent: A ~ B
, 
sq_stable: SqStable(P)
, 
subtype_rel: A ⊆r B
, 
ext-eq: A ≡ B
, 
istype: istype(T)
, 
iff: P 
⇐⇒ Q
, 
rev_implies: P 
⇐ Q
, 
inject: Inj(A;B;f)
, 
uiff: uiff(P;Q)
Lemmas referenced : 
le_witness_for_triv, 
equipollent_wf, 
int_seg_wf, 
inject_wf, 
length_wf, 
not_wf, 
assert_wf, 
select_wf, 
int_seg_properties, 
nat_properties, 
decidable__le, 
full-omega-unsat, 
intformand_wf, 
intformnot_wf, 
intformle_wf, 
itermConstant_wf, 
itermVar_wf, 
istype-int, 
int_formula_prop_and_lemma, 
istype-void, 
int_formula_prop_not_lemma, 
int_formula_prop_le_lemma, 
int_term_value_constant_lemma, 
int_term_value_var_lemma, 
int_formula_prop_wf, 
decidable__lt, 
intformless_wf, 
int_formula_prop_less_lemma, 
istype-universe, 
nat_wf, 
list_wf, 
bool_wf, 
equipollent-partition, 
length_wf_nat, 
equipollent_same, 
decidable__assert, 
equipollent-subtract2, 
filter_wf5, 
subtype_rel_dep_function, 
l_member_wf, 
subtract_wf, 
equipollent_functionality_wrt_equipollent, 
equipollent_weakening_ext-eq, 
ext-eq_weakening, 
equipollent-nsub, 
equipollent_inversion, 
pigeon-hole, 
itermSubtract_wf, 
int_term_value_subtract_lemma, 
le_wf, 
subtract-is-int-iff, 
intformeq_wf, 
int_formula_prop_eq_lemma, 
false_wf, 
equipollent_transitivity, 
subtype_rel_self, 
set_wf, 
sq_stable__not, 
subtype_rel_sets, 
equipollent-filter, 
compose_wf, 
injection-composition, 
satisfiable-full-omega-tt
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
Error :isect_memberFormation_alt, 
introduction, 
cut, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
thin, 
productElimination, 
equalityTransitivity, 
hypothesis, 
equalitySymmetry, 
independent_isectElimination, 
Error :universeIsType, 
hypothesisEquality, 
natural_numberEquality, 
setElimination, 
rename, 
sqequalRule, 
Error :isect_memberEquality_alt, 
because_Cache, 
setEquality, 
cumulativity, 
applyEquality, 
functionExtensionality, 
dependent_functionElimination, 
unionElimination, 
approximateComputation, 
independent_functionElimination, 
Error :dependent_pairFormation_alt, 
Error :lambdaEquality_alt, 
int_eqEquality, 
voidElimination, 
independent_pairFormation, 
imageElimination, 
Error :functionIsType, 
Error :setIsType, 
Error :inhabitedIsType, 
universeEquality, 
Error :lambdaFormation_alt, 
computeAll, 
voidEquality, 
isect_memberEquality, 
intEquality, 
lambdaEquality, 
lemma_by_obid, 
productEquality, 
dependent_pairFormation, 
functionEquality, 
lambdaFormation, 
baseClosed, 
imageMemberEquality, 
dependent_set_memberEquality, 
promote_hyp, 
Error :dependent_set_memberEquality_alt, 
applyLambdaEquality, 
Error :equalityIsType1, 
pointwiseFunctionality, 
baseApply, 
closedConclusion
Latex:
\mforall{}[A:Type].  \mforall{}[P:A  {}\mrightarrow{}  \mBbbB{}].  \mforall{}[L:A  List].  \mforall{}[T:Type].  \mforall{}[k:\mBbbN{}].  \mforall{}[f:\{i:\mBbbN{}||L|||  \mneg{}\muparrow{}P[L[i]]\}    {}\mrightarrow{}  T].
    ((||L||  -  k)  \mleq{}  ||filter(P;L)||)  supposing  (T  \msim{}  \mBbbN{}k  and  Inj(\{i:\mBbbN{}||L|||  \mneg{}\muparrow{}P[L[i]]\}  ;T;f))
Date html generated:
2019_06_20-PM-02_19_48
Last ObjectModification:
2018_10_05-PM-04_11_09
Theory : equipollence!!cardinality!
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