Nuprl Lemma : bexists_iff_exists_nth
∀s:DSet. ∀f:|s| ⟶ 𝔹. ∀as:|s| List.  (↑∃b x(:|s|) ∈ as. f[x] 
⇐⇒ ∃n:ℕ||as||. (↑f[as[n]]))
Proof
Definitions occuring in Statement : 
mon_for: For{g} x ∈ as. f[x]
, 
select: L[n]
, 
length: ||as||
, 
list: T List
, 
int_seg: {i..j-}
, 
assert: ↑b
, 
bool: 𝔹
, 
so_apply: x[s]
, 
all: ∀x:A. B[x]
, 
exists: ∃x:A. B[x]
, 
iff: P 
⇐⇒ Q
, 
function: x:A ⟶ B[x]
, 
natural_number: $n
, 
bor_mon: <𝔹,∨b>
, 
dset: DSet
, 
set_car: |p|
Definitions unfolded in proof : 
all: ∀x:A. B[x]
, 
member: t ∈ T
, 
uall: ∀[x:A]. B[x]
, 
dset: DSet
, 
so_lambda: λ2x.t[x]
, 
subtype_rel: A ⊆r B
, 
so_apply: x[s]
, 
int_seg: {i..j-}
, 
uimplies: b supposing a
, 
guard: {T}
, 
lelt: i ≤ j < k
, 
and: P ∧ Q
, 
decidable: Dec(P)
, 
or: P ∨ Q
, 
not: ¬A
, 
implies: P 
⇒ Q
, 
satisfiable_int_formula: satisfiable_int_formula(fmla)
, 
exists: ∃x:A. B[x]
, 
false: False
, 
top: Top
, 
prop: ℙ
, 
less_than: a < b
, 
squash: ↓T
, 
select: L[n]
, 
nil: []
, 
it: ⋅
, 
so_lambda: λ2x y.t[x; y]
, 
so_apply: x[s1;s2]
, 
bor_mon: <𝔹,∨b>
, 
grp_id: e
, 
pi2: snd(t)
, 
pi1: fst(t)
, 
assert: ↑b
, 
ifthenelse: if b then t else f fi 
, 
bfalse: ff
, 
grp_op: *
, 
infix_ap: x f y
, 
iff: P 
⇐⇒ Q
, 
rev_implies: P 
⇐ Q
, 
ge: i ≥ j 
, 
le: A ≤ B
, 
less_than': less_than'(a;b)
, 
nat_plus: ℕ+
, 
true: True
, 
uiff: uiff(P;Q)
, 
rev_uimplies: rev_uimplies(P;Q)
, 
subtract: n - m
Lemmas referenced : 
list_wf, 
set_car_wf, 
bool_wf, 
dset_wf, 
list_induction, 
iff_wf, 
assert_wf, 
mon_for_wf, 
bor_mon_wf, 
exists_wf, 
int_seg_wf, 
length_wf, 
select_wf, 
int_seg_properties, 
decidable__le, 
full-omega-unsat, 
intformand_wf, 
intformnot_wf, 
intformle_wf, 
itermConstant_wf, 
itermVar_wf, 
istype-int, 
int_formula_prop_and_lemma, 
istype-void, 
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, 
mon_for_nil_lemma, 
length_of_nil_lemma, 
stuck-spread, 
istype-base, 
mon_for_cons_lemma, 
length_of_cons_lemma, 
iff_weakening_uiff, 
bor_wf, 
or_wf, 
assert_of_bor, 
cons_wf, 
non_neg_length, 
itermAdd_wf, 
int_term_value_add_lemma, 
istype-false, 
add_nat_plus, 
length_wf_nat, 
less_than_wf, 
nat_plus_properties, 
add-is-int-iff, 
intformeq_wf, 
int_formula_prop_eq_lemma, 
false_wf, 
le_wf, 
assert_functionality_wrt_uiff, 
select_cons_hd, 
add-member-int_seg2, 
subtract_wf, 
itermSubtract_wf, 
int_term_value_subtract_lemma, 
add-subtract-cancel, 
select_cons_tl, 
add-associates, 
add-swap, 
add-commutes, 
zero-add, 
decidable__equal_int
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
lambdaFormation_alt, 
universeIsType, 
cut, 
introduction, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
thin, 
setElimination, 
rename, 
hypothesisEquality, 
hypothesis, 
functionIsType, 
sqequalRule, 
lambdaEquality_alt, 
dependent_functionElimination, 
applyEquality, 
because_Cache, 
natural_numberEquality, 
independent_isectElimination, 
productElimination, 
unionElimination, 
approximateComputation, 
independent_functionElimination, 
dependent_pairFormation_alt, 
int_eqEquality, 
isect_memberEquality_alt, 
voidElimination, 
independent_pairFormation, 
imageElimination, 
baseClosed, 
inhabitedIsType, 
promote_hyp, 
productIsType, 
addEquality, 
unionIsType, 
dependent_set_memberEquality_alt, 
imageMemberEquality, 
equalityTransitivity, 
equalitySymmetry, 
applyLambdaEquality, 
pointwiseFunctionality, 
baseApply, 
closedConclusion, 
equalityIsType1, 
inlFormation_alt, 
inrFormation_alt
Latex:
\mforall{}s:DSet.  \mforall{}f:|s|  {}\mrightarrow{}  \mBbbB{}.  \mforall{}as:|s|  List.    (\muparrow{}\mexists{}b  x(:|s|)  \mmember{}  as.  f[x]  \mLeftarrow{}{}\mRightarrow{}  \mexists{}n:\mBbbN{}||as||.  (\muparrow{}f[as[n]]))
Date html generated:
2019_10_16-PM-01_03_22
Last ObjectModification:
2018_10_08-AM-11_16_52
Theory : list_2
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