Nuprl Lemma : filter-equal
∀[T:Type]. ∀[P:T ⟶ 𝔹]. ∀[L1,L2:T List].
  (filter(P;L1) = filter(P;L2) ∈ (T List)) supposing 
     ((∀i:ℕ||L1||. ((L1[i] = L2[i] ∈ T) ∨ ((¬↑(P L1[i])) ∧ (¬↑(P L2[i]))))) and 
     (||L1|| = ||L2|| ∈ ℤ))
Proof
Definitions occuring in Statement : 
select: L[n]
, 
length: ||as||
, 
filter: filter(P;l)
, 
list: T List
, 
int_seg: {i..j-}
, 
assert: ↑b
, 
bool: 𝔹
, 
uimplies: b supposing a
, 
uall: ∀[x:A]. B[x]
, 
all: ∀x:A. B[x]
, 
not: ¬A
, 
or: P ∨ Q
, 
and: P ∧ Q
, 
apply: f a
, 
function: x:A ⟶ B[x]
, 
natural_number: $n
, 
int: ℤ
, 
universe: Type
, 
equal: s = t ∈ T
Definitions unfolded in proof : 
true: True
, 
assert: ↑b
, 
iff: P 
⇐⇒ Q
, 
rev_implies: P 
⇐ Q
, 
bfalse: ff
, 
ifthenelse: if b then t else f fi 
, 
btrue: tt
, 
unit: Unit
, 
bool: 𝔹
, 
uall: ∀[x:A]. B[x]
, 
member: t ∈ T
, 
all: ∀x:A. B[x]
, 
nat: ℕ
, 
implies: P 
⇒ Q
, 
false: False
, 
ge: i ≥ j 
, 
uimplies: b supposing a
, 
not: ¬A
, 
satisfiable_int_formula: satisfiable_int_formula(fmla)
, 
exists: ∃x:A. B[x]
, 
top: Top
, 
and: P ∧ Q
, 
prop: ℙ
, 
or: P ∨ Q
, 
select: L[n]
, 
nil: []
, 
it: ⋅
, 
so_lambda: λ2x y.t[x; y]
, 
so_apply: x[s1;s2]
, 
int_seg: {i..j-}
, 
lelt: i ≤ j < k
, 
cons: [a / b]
, 
colength: colength(L)
, 
guard: {T}
, 
so_lambda: λ2x.t[x]
, 
so_apply: x[s]
, 
sq_type: SQType(T)
, 
le: A ≤ B
, 
subtype_rel: A ⊆r B
, 
decidable: Dec(P)
, 
less_than: a < b
, 
squash: ↓T
, 
less_than': less_than'(a;b)
, 
uiff: uiff(P;Q)
, 
nat_plus: ℕ+
Lemmas referenced : 
select-cons, 
squash_wf, 
true_wf, 
add-subtract-cancel, 
bool_subtype_base, 
iff_imp_equal_bool, 
le_int_wf, 
bfalse_wf, 
iff_functionality_wrt_iff, 
iff_weakening_uiff, 
assert_of_le_int, 
iff_weakening_equal, 
assert_of_bnot, 
eqff_to_assert, 
uiff_transitivity, 
eqtt_to_assert, 
nat_properties, 
full-omega-unsat, 
intformand_wf, 
intformle_wf, 
itermConstant_wf, 
itermVar_wf, 
intformless_wf, 
istype-int, 
int_formula_prop_and_lemma, 
istype-void, 
int_formula_prop_le_lemma, 
int_term_value_constant_lemma, 
int_term_value_var_lemma, 
int_formula_prop_less_lemma, 
int_formula_prop_wf, 
ge_wf, 
istype-less_than, 
list-cases, 
length_of_nil_lemma, 
stuck-spread, 
istype-base, 
filter_nil_lemma, 
nil_wf, 
int_seg_wf, 
int_seg_properties, 
product_subtype_list, 
colength-cons-not-zero, 
subtract-1-ge-0, 
subtype_base_sq, 
intformeq_wf, 
int_formula_prop_eq_lemma, 
set_subtype_base, 
int_subtype_base, 
spread_cons_lemma, 
length_of_cons_lemma, 
filter_cons_lemma, 
non_neg_length, 
itermAdd_wf, 
int_term_value_add_lemma, 
length_wf, 
colength_wf_list, 
decidable__le, 
intformnot_wf, 
int_formula_prop_not_lemma, 
istype-le, 
decidable__equal_int, 
subtract_wf, 
itermSubtract_wf, 
int_term_value_subtract_lemma, 
le_wf, 
add-is-int-iff, 
false_wf, 
select_wf, 
cons_wf, 
decidable__lt, 
istype-assert, 
istype-nat, 
list_wf, 
bool_wf, 
istype-universe, 
istype-false, 
add_nat_plus, 
length_wf_nat, 
nat_plus_properties, 
equal-wf-T-base, 
assert_wf, 
bnot_wf, 
not_wf, 
assert_elim, 
not_assert_elim, 
btrue_neq_bfalse
Rules used in proof : 
imageMemberEquality, 
cumulativity, 
equalityElimination, 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
Error :isect_memberFormation_alt, 
introduction, 
cut, 
thin, 
Error :lambdaFormation_alt, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
hypothesisEquality, 
hypothesis, 
setElimination, 
rename, 
intWeakElimination, 
natural_numberEquality, 
independent_isectElimination, 
approximateComputation, 
independent_functionElimination, 
Error :dependent_pairFormation_alt, 
Error :lambdaEquality_alt, 
int_eqEquality, 
dependent_functionElimination, 
Error :isect_memberEquality_alt, 
voidElimination, 
sqequalRule, 
independent_pairFormation, 
Error :universeIsType, 
axiomEquality, 
Error :isectIsTypeImplies, 
Error :inhabitedIsType, 
Error :functionIsTypeImplies, 
unionElimination, 
baseClosed, 
because_Cache, 
Error :functionIsType, 
equalityTransitivity, 
equalitySymmetry, 
productElimination, 
Error :equalityIstype, 
sqequalBase, 
promote_hyp, 
hypothesis_subsumption, 
instantiate, 
applyLambdaEquality, 
addEquality, 
applyEquality, 
Error :dependent_set_memberEquality_alt, 
imageElimination, 
baseApply, 
closedConclusion, 
intEquality, 
pointwiseFunctionality, 
Error :unionIsType, 
Error :productIsType, 
universeEquality
Latex:
\mforall{}[T:Type].  \mforall{}[P:T  {}\mrightarrow{}  \mBbbB{}].  \mforall{}[L1,L2:T  List].
    (filter(P;L1)  =  filter(P;L2))  supposing 
          ((\mforall{}i:\mBbbN{}||L1||.  ((L1[i]  =  L2[i])  \mvee{}  ((\mneg{}\muparrow{}(P  L1[i]))  \mwedge{}  (\mneg{}\muparrow{}(P  L2[i])))))  and 
          (||L1||  =  ||L2||))
Date html generated:
2019_06_20-PM-02_13_14
Last ObjectModification:
2019_06_20-PM-02_08_13
Theory : list_1
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