Nuprl Lemma : filter-for-max
∀[A:Type]. ∀[l:A List]. ∀[m:ℤ]. ∀[g:A ⟶ ℤ].
  (||filter(λe.(g[e] =z m);l)|| ≥ 1 ) supposing ((imax-list(map(λe.g[e];l)) = m ∈ ℤ) and 0 < ||l||)
Proof
Definitions occuring in Statement : 
imax-list: imax-list(L)
, 
length: ||as||
, 
filter: filter(P;l)
, 
map: map(f;as)
, 
list: T List
, 
eq_int: (i =z j)
, 
less_than: a < b
, 
uimplies: b supposing a
, 
uall: ∀[x:A]. B[x]
, 
so_apply: x[s]
, 
ge: i ≥ j 
, 
lambda: λx.A[x]
, 
function: x:A ⟶ B[x]
, 
natural_number: $n
, 
int: ℤ
, 
universe: Type
, 
equal: s = t ∈ T
Definitions unfolded in proof : 
so_apply: x[s]
, 
uall: ∀[x:A]. B[x]
, 
member: t ∈ T
, 
uimplies: b supposing a
, 
ge: i ≥ j 
, 
le: A ≤ B
, 
and: P ∧ Q
, 
not: ¬A
, 
implies: P 
⇒ Q
, 
false: False
, 
prop: ℙ
, 
top: Top
, 
subtype_rel: A ⊆r B
, 
all: ∀x:A. B[x]
, 
sq_type: SQType(T)
, 
guard: {T}
, 
l_member: (x ∈ l)
, 
exists: ∃x:A. B[x]
, 
cand: A c∧ B
, 
squash: ↓T
, 
nat: ℕ
, 
true: True
, 
iff: P 
⇐⇒ Q
, 
int_seg: {i..j-}
, 
lelt: i ≤ j < k
, 
decidable: Dec(P)
, 
or: P ∨ Q
, 
satisfiable_int_formula: satisfiable_int_formula(fmla)
, 
rev_implies: P 
⇐ Q
, 
uiff: uiff(P;Q)
, 
rev_uimplies: rev_uimplies(P;Q)
Lemmas referenced : 
less_than'_wf, 
length_wf, 
filter_wf5, 
eq_int_wf, 
l_member_wf, 
equal-wf-T-base, 
imax-list_wf, 
map-length, 
int_subtype_base, 
less_than_wf, 
pos_length, 
imax-list-member, 
map_wf, 
subtype_base_sq, 
list_wf, 
squash_wf, 
true_wf, 
map_length, 
iff_weakening_equal, 
equal_wf, 
map_select, 
lelt_wf, 
member_filter, 
select_wf, 
nat_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, 
select_member, 
assert_of_eq_int, 
eta_conv, 
null_nil_lemma, 
btrue_wf, 
member-implies-null-eq-bfalse, 
btrue_neq_bfalse
Rules used in proof : 
sqequalSubstitution, 
sqequalRule, 
sqequalReflexivity, 
sqequalTransitivity, 
computationStep, 
isect_memberFormation, 
introduction, 
cut, 
sqequalHypSubstitution, 
productElimination, 
thin, 
independent_pairEquality, 
lambdaEquality, 
dependent_functionElimination, 
hypothesisEquality, 
because_Cache, 
extract_by_obid, 
isectElimination, 
cumulativity, 
applyEquality, 
functionExtensionality, 
setElimination, 
rename, 
hypothesis, 
setEquality, 
natural_numberEquality, 
axiomEquality, 
equalityTransitivity, 
equalitySymmetry, 
independent_isectElimination, 
isect_memberEquality, 
voidElimination, 
voidEquality, 
functionEquality, 
intEquality, 
lambdaFormation, 
instantiate, 
independent_functionElimination, 
baseClosed, 
imageElimination, 
imageMemberEquality, 
universeEquality, 
dependent_set_memberEquality, 
independent_pairFormation, 
unionElimination, 
dependent_pairFormation, 
int_eqEquality, 
computeAll, 
hyp_replacement, 
applyLambdaEquality
Latex:
\mforall{}[A:Type].  \mforall{}[l:A  List].  \mforall{}[m:\mBbbZ{}].  \mforall{}[g:A  {}\mrightarrow{}  \mBbbZ{}].
    (||filter(\mlambda{}e.(g[e]  =\msubz{}  m);l)||  \mgeq{}  1  )  supposing  ((imax-list(map(\mlambda{}e.g[e];l))  =  m)  and  0  <  ||l||)
Date html generated:
2017_04_17-AM-07_50_39
Last ObjectModification:
2017_02_27-PM-04_24_30
Theory : list_1
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