Nuprl Lemma : split_tail_lemma
∀[A:Type]
  ∀f:A ⟶ 𝔹. ∀L:A List.
    (∀a∈L.∃L1,L2:A List. (((L = (L1 @ L2) ∈ (A List)) ∧ (a ∈ L2) ∧ (∀b∈L2.↑f[b])) ∧ ¬↑f[last(L1)] supposing ¬↑null(L1)) 
          supposing (∀b≥a∈L.↑f[b]))
Proof
Definitions occuring in Statement : 
l_all_since: (∀x≥a∈L.P[x])
, 
l_all: (∀x∈L.P[x])
, 
last: last(L)
, 
l_member: (x ∈ l)
, 
null: null(as)
, 
append: as @ bs
, 
list: T List
, 
assert: ↑b
, 
bool: 𝔹
, 
uimplies: b supposing a
, 
uall: ∀[x:A]. B[x]
, 
so_apply: x[s]
, 
all: ∀x:A. B[x]
, 
exists: ∃x:A. B[x]
, 
not: ¬A
, 
and: P ∧ Q
, 
function: x:A ⟶ B[x]
, 
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
, 
uimplies: b supposing a
, 
so_apply: x[s]
, 
and: P ∧ Q
, 
top: Top
, 
iff: P 
⇐⇒ Q
, 
rev_implies: P 
⇐ Q
, 
implies: P 
⇒ Q
, 
l_all_since: (∀x≥a∈L.P[x])
, 
exists: ∃x:A. B[x]
, 
cand: A c∧ B
, 
squash: ↓T
, 
true: True
, 
subtype_rel: A ⊆r B
, 
guard: {T}
, 
not: ¬A
, 
false: False
, 
split_tail: split_tail(L | ∀x.f[x])
, 
so_lambda: so_lambda(x,y,z.t[x; y; z])
, 
so_apply: x[s1;s2;s3]
, 
pi1: fst(t)
, 
assert: ↑b
, 
ifthenelse: if b then t else f fi 
, 
btrue: tt
, 
bool: 𝔹
, 
unit: Unit
, 
it: ⋅
, 
uiff: uiff(P;Q)
, 
bfalse: ff
, 
or: P ∨ Q
, 
sq_type: SQType(T)
, 
bnot: ¬bb
Lemmas referenced : 
l_all_iff, 
l_member_wf, 
isect_wf, 
l_all_since_wf, 
assert_wf, 
exists_wf, 
list_wf, 
equal_wf, 
append_wf, 
length_wf, 
length-append, 
l_all_wf, 
not_wf, 
null_wf, 
last_wf, 
assert_witness, 
l_before_wf, 
bool_wf, 
split_tail_wf, 
pi1_wf, 
pi2_wf, 
squash_wf, 
true_wf, 
split_tail_rel, 
iff_weakening_equal, 
all_wf, 
split_tail_max, 
split_tail_correct, 
l_all_fwd, 
list_induction, 
list_ind_nil_lemma, 
null_nil_lemma, 
list_ind_cons_lemma, 
eqtt_to_assert, 
eqff_to_assert, 
bool_cases_sqequal, 
subtype_base_sq, 
bool_subtype_base, 
assert-bnot, 
list_ind_wf, 
nil_wf, 
cons_wf, 
null_cons_lemma, 
false_wf, 
assert_functionality_wrt_uiff, 
assert_elim, 
bfalse_wf, 
btrue_neq_bfalse, 
last_cons, 
last_singleton
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation, 
lambdaFormation, 
cut, 
introduction, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
thin, 
hypothesisEquality, 
dependent_functionElimination, 
sqequalRule, 
lambdaEquality, 
cumulativity, 
hypothesis, 
setElimination, 
rename, 
applyEquality, 
functionExtensionality, 
because_Cache, 
productEquality, 
applyLambdaEquality, 
isect_memberEquality, 
voidElimination, 
voidEquality, 
setEquality, 
isectEquality, 
independent_isectElimination, 
productElimination, 
independent_functionElimination, 
independent_pairEquality, 
functionEquality, 
universeEquality, 
dependent_pairFormation, 
equalityTransitivity, 
equalitySymmetry, 
imageElimination, 
natural_numberEquality, 
imageMemberEquality, 
baseClosed, 
independent_pairFormation, 
addLevel, 
existsFunctionality, 
andLevelFunctionality, 
existsLevelFunctionality, 
unionElimination, 
equalityElimination, 
promote_hyp, 
instantiate, 
impliesFunctionality, 
levelHypothesis
Latex:
\mforall{}[A:Type]
    \mforall{}f:A  {}\mrightarrow{}  \mBbbB{}.  \mforall{}L:A  List.
        (\mforall{}a\mmember{}L.\mexists{}L1,L2:A  List
                      (((L  =  (L1  @  L2))  \mwedge{}  (a  \mmember{}  L2)  \mwedge{}  (\mforall{}b\mmember{}L2.\muparrow{}f[b]))  \mwedge{}  \mneg{}\muparrow{}f[last(L1)]  supposing  \mneg{}\muparrow{}null(L1)) 
                    supposing  (\mforall{}b\mgeq{}a\mmember{}L.\muparrow{}f[b]))
Date html generated:
2017_10_01-AM-08_34_59
Last ObjectModification:
2017_07_26-PM-04_25_36
Theory : list!
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