Nuprl Lemma : append_split
∀[T:Type]
  ∀L:T List
    ∀[P:T ⟶ ℙ]
      ((∀x:ℕ||L||. Dec(P L[x]))
      
⇒ (∀i,j:ℕ||L||.  ((P L[i]) 
⇒ P L[j] supposing i < j))
      
⇒ (∃L1,L2:T List
           (((L = (L1 @ L2) ∈ (T List)) ∧ (∀i:ℕ||L1||. (¬(P L1[i]))) ∧ (∀i:ℕ||L2||. (P L2[i])))
           ∧ (∀x∈L.(P x) 
⇒ (x ∈ L2)))))
Proof
Definitions occuring in Statement : 
l_all: (∀x∈L.P[x])
, 
l_member: (x ∈ l)
, 
select: L[n]
, 
length: ||as||
, 
append: as @ bs
, 
list: T List
, 
int_seg: {i..j-}
, 
less_than: a < b
, 
decidable: Dec(P)
, 
uimplies: b supposing a
, 
uall: ∀[x:A]. B[x]
, 
prop: ℙ
, 
all: ∀x:A. B[x]
, 
exists: ∃x:A. B[x]
, 
not: ¬A
, 
implies: P 
⇒ Q
, 
and: P ∧ Q
, 
apply: f a
, 
function: x:A ⟶ B[x]
, 
natural_number: $n
, 
universe: Type
, 
equal: s = t ∈ T
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x]
, 
all: ∀x:A. B[x]
, 
member: t ∈ T
, 
so_lambda: λ2x.t[x]
, 
prop: ℙ
, 
implies: P 
⇒ Q
, 
int_seg: {i..j-}
, 
uimplies: b supposing a
, 
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
, 
top: Top
, 
less_than: a < b
, 
squash: ↓T
, 
so_apply: x[s]
, 
subtype_rel: A ⊆r B
, 
select: L[n]
, 
nil: []
, 
it: ⋅
, 
so_lambda: λ2x y.t[x; y]
, 
so_apply: x[s1;s2]
, 
append: as @ bs
, 
so_lambda: so_lambda(x,y,z.t[x; y; z])
, 
so_apply: x[s1;s2;s3]
, 
cand: A c∧ B
, 
ge: i ≥ j 
, 
le: A ≤ B
, 
uiff: uiff(P;Q)
, 
subtract: n - m
, 
less_than': less_than'(a;b)
, 
nat_plus: ℕ+
, 
true: True
, 
cons: [a / b]
, 
iff: P 
⇐⇒ Q
, 
sq_type: SQType(T)
, 
rev_implies: P 
⇐ Q
, 
l_all: (∀x∈L.P[x])
Lemmas referenced : 
list_induction, 
uall_wf, 
all_wf, 
int_seg_wf, 
length_wf, 
decidable_wf, 
select_wf, 
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, 
less_than_wf, 
exists_wf, 
list_wf, 
equal_wf, 
append_wf, 
length-append, 
not_wf, 
l_all_wf, 
l_member_wf, 
length_of_nil_lemma, 
stuck-spread, 
base_wf, 
length_of_cons_lemma, 
nil_wf, 
list_ind_nil_lemma, 
l_all_nil, 
equal-wf-base-T, 
intformeq_wf, 
int_formula_prop_eq_lemma, 
l_all_wf_nil, 
cons_wf, 
non_neg_length, 
itermAdd_wf, 
int_term_value_add_lemma, 
add-member-int_seg2, 
subtract_wf, 
itermSubtract_wf, 
int_term_value_subtract_lemma, 
lelt_wf, 
select_cons_tl_sq, 
member-less_than, 
select-cons-tl, 
add-subtract-cancel, 
false_wf, 
add_nat_plus, 
length_wf_nat, 
nat_plus_wf, 
nat_plus_properties, 
add-is-int-iff, 
squash_wf, 
true_wf, 
select-cons-hd, 
select_append_front, 
iff_weakening_equal, 
length_zero, 
decidable__equal_int, 
subtype_base_sq, 
int_subtype_base, 
select_cons_tl, 
l_all_cons, 
cons_member, 
list_ind_cons_lemma
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation, 
lambdaFormation, 
cut, 
thin, 
instantiate, 
introduction, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
cumulativity, 
hypothesisEquality, 
sqequalRule, 
lambdaEquality, 
functionEquality, 
because_Cache, 
universeEquality, 
natural_numberEquality, 
hypothesis, 
applyEquality, 
functionExtensionality, 
setElimination, 
rename, 
independent_isectElimination, 
productElimination, 
dependent_functionElimination, 
unionElimination, 
dependent_pairFormation, 
int_eqEquality, 
intEquality, 
isect_memberEquality, 
voidElimination, 
voidEquality, 
independent_pairFormation, 
computeAll, 
imageElimination, 
isectEquality, 
productEquality, 
applyLambdaEquality, 
setEquality, 
independent_functionElimination, 
baseClosed, 
equalityTransitivity, 
equalitySymmetry, 
addEquality, 
dependent_set_memberEquality, 
imageMemberEquality, 
pointwiseFunctionality, 
promote_hyp, 
baseApply, 
closedConclusion, 
hyp_replacement, 
inlFormation, 
inrFormation
Latex:
\mforall{}[T:Type]
    \mforall{}L:T  List
        \mforall{}[P:T  {}\mrightarrow{}  \mBbbP{}]
            ((\mforall{}x:\mBbbN{}||L||.  Dec(P  L[x]))
            {}\mRightarrow{}  (\mforall{}i,j:\mBbbN{}||L||.    ((P  L[i])  {}\mRightarrow{}  P  L[j]  supposing  i  <  j))
            {}\mRightarrow{}  (\mexists{}L1,L2:T  List
                      (((L  =  (L1  @  L2))  \mwedge{}  (\mforall{}i:\mBbbN{}||L1||.  (\mneg{}(P  L1[i])))  \mwedge{}  (\mforall{}i:\mBbbN{}||L2||.  (P  L2[i])))
                      \mwedge{}  (\mforall{}x\mmember{}L.(P  x)  {}\mRightarrow{}  (x  \mmember{}  L2)))))
Date html generated:
2017_10_01-AM-08_34_35
Last ObjectModification:
2017_07_26-PM-04_25_29
Theory : list!
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