Nuprl Lemma : sorted-by-filter
∀[T:Type]. ∀[R:T ⟶ T ⟶ ℙ].  ∀P:T ⟶ 𝔹. ∀L:T List.  (sorted-by(R;L) 
⇒ sorted-by(R;filter(P;L)))
Proof
Definitions occuring in Statement : 
sorted-by: sorted-by(R;L)
, 
filter: filter(P;l)
, 
list: T List
, 
bool: 𝔹
, 
uall: ∀[x:A]. B[x]
, 
prop: ℙ
, 
all: ∀x:A. B[x]
, 
implies: P 
⇒ Q
, 
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]
, 
implies: P 
⇒ Q
, 
prop: ℙ
, 
subtype_rel: A ⊆r B
, 
so_apply: x[s]
, 
uimplies: b supposing a
, 
top: Top
, 
sorted-by: sorted-by(R;L)
, 
int_seg: {i..j-}
, 
guard: {T}
, 
lelt: i ≤ j < k
, 
and: P ∧ Q
, 
decidable: Dec(P)
, 
or: P ∨ Q
, 
satisfiable_int_formula: satisfiable_int_formula(fmla)
, 
exists: ∃x:A. B[x]
, 
false: False
, 
not: ¬A
, 
iff: P 
⇐⇒ Q
, 
rev_implies: P 
⇐ Q
, 
cand: A c∧ B
, 
bool: 𝔹
, 
unit: Unit
, 
it: ⋅
, 
btrue: tt
, 
uiff: uiff(P;Q)
, 
ifthenelse: if b then t else f fi 
, 
bfalse: ff
Lemmas referenced : 
list_induction, 
sorted-by_wf, 
subtype_rel_dep_function, 
l_member_wf, 
subtype_rel_self, 
set_wf, 
filter_wf5, 
bool_wf, 
list_wf, 
filter_nil_lemma, 
filter_cons_lemma, 
int_seg_wf, 
length_wf, 
nil_wf, 
all_wf, 
select_wf, 
length_of_nil_lemma, 
int_seg_properties, 
decidable__le, 
satisfiable-full-omega-tt, 
intformand_wf, 
intformnot_wf, 
intformle_wf, 
itermConstant_wf, 
itermVar_wf, 
int_formula_prop_and_lemma, 
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, 
sorted-by-cons, 
cons_wf, 
equal-wf-T-base, 
assert_wf, 
bnot_wf, 
not_wf, 
eqtt_to_assert, 
uiff_transitivity, 
eqff_to_assert, 
assert_of_bnot, 
equal_wf, 
l_all_iff, 
member_filter
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation, 
lambdaFormation, 
cut, 
thin, 
introduction, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
hypothesisEquality, 
sqequalRule, 
lambdaEquality, 
functionEquality, 
cumulativity, 
applyEquality, 
instantiate, 
universeEquality, 
setEquality, 
hypothesis, 
independent_isectElimination, 
setElimination, 
rename, 
because_Cache, 
dependent_functionElimination, 
independent_functionElimination, 
isect_memberEquality, 
voidElimination, 
voidEquality, 
natural_numberEquality, 
functionExtensionality, 
productElimination, 
unionElimination, 
dependent_pairFormation, 
int_eqEquality, 
intEquality, 
independent_pairFormation, 
computeAll, 
equalityTransitivity, 
equalitySymmetry, 
baseClosed, 
equalityElimination
Latex:
\mforall{}[T:Type].  \mforall{}[R:T  {}\mrightarrow{}  T  {}\mrightarrow{}  \mBbbP{}].    \mforall{}P:T  {}\mrightarrow{}  \mBbbB{}.  \mforall{}L:T  List.    (sorted-by(R;L)  {}\mRightarrow{}  sorted-by(R;filter(P;L)))
Date html generated:
2017_04_17-AM-07_43_36
Last ObjectModification:
2017_02_27-PM-04_16_24
Theory : list_1
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