Nuprl Lemma : decidable__exists_iseg
∀[T:Type]. ∀[P:(T List) ⟶ ℙ].  ((∀L:T List. Dec(P[L])) 
⇒ (∀L:T List. Dec(∃L':T List. (L' ≤ L ∧ P[L']))))
Proof
Definitions occuring in Statement : 
iseg: l1 ≤ l2
, 
list: T List
, 
decidable: Dec(P)
, 
uall: ∀[x:A]. B[x]
, 
prop: ℙ
, 
so_apply: x[s]
, 
all: ∀x:A. B[x]
, 
exists: ∃x:A. B[x]
, 
implies: P 
⇒ Q
, 
and: P ∧ Q
, 
function: x:A ⟶ B[x]
, 
universe: Type
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x]
, 
implies: P 
⇒ Q
, 
all: ∀x:A. B[x]
, 
member: t ∈ T
, 
int_seg: {i..j-}
, 
lelt: i ≤ j < k
, 
and: P ∧ Q
, 
le: A ≤ B
, 
uimplies: b supposing a
, 
not: ¬A
, 
satisfiable_int_formula: satisfiable_int_formula(fmla)
, 
exists: ∃x:A. B[x]
, 
false: False
, 
prop: ℙ
, 
decidable: Dec(P)
, 
or: P ∨ Q
, 
subtype_rel: A ⊆r B
, 
so_lambda: λ2x.t[x]
, 
so_apply: x[s]
, 
guard: {T}
, 
sq_type: SQType(T)
, 
nat: ℕ
, 
ge: i ≥ j 
, 
less_than: a < b
, 
squash: ↓T
, 
cons: [a / b]
, 
assert: ↑b
, 
ifthenelse: if b then t else f fi 
, 
bfalse: ff
, 
iff: P 
⇐⇒ Q
, 
rev_implies: P 
⇐ Q
, 
uiff: uiff(P;Q)
, 
int_iseg: {i...j}
, 
cand: A c∧ B
, 
btrue: tt
, 
iseg: l1 ≤ l2
, 
less_than': less_than'(a;b)
, 
true: True
, 
last: last(L)
, 
subtract: n - m
, 
length: ||as||
, 
list_ind: list_ind, 
nil: []
, 
it: ⋅
Lemmas referenced : 
int_seg_properties, 
full-omega-unsat, 
intformand_wf, 
intformless_wf, 
itermVar_wf, 
itermConstant_wf, 
intformle_wf, 
istype-int, 
int_formula_prop_and_lemma, 
int_formula_prop_less_lemma, 
int_term_value_var_lemma, 
int_term_value_constant_lemma, 
int_formula_prop_le_lemma, 
int_formula_prop_wf, 
int_seg_wf, 
decidable__equal_int, 
subtract_wf, 
subtype_base_sq, 
set_subtype_base, 
lelt_wf, 
int_subtype_base, 
intformnot_wf, 
intformeq_wf, 
itermSubtract_wf, 
int_formula_prop_not_lemma, 
int_formula_prop_eq_lemma, 
int_term_value_subtract_lemma, 
decidable__le, 
decidable__lt, 
istype-le, 
istype-less_than, 
subtype_rel_self, 
non_neg_length, 
nat_properties, 
length_wf, 
decidable__assert, 
null_wf, 
list-cases, 
product_subtype_list, 
null_cons_lemma, 
last-lemma-sq, 
pos_length, 
iff_transitivity, 
not_wf, 
equal-wf-T-base, 
list_wf, 
assert_wf, 
bnot_wf, 
iff_weakening_uiff, 
assert_of_null, 
istype-assert, 
nil_wf, 
length_of_nil_lemma, 
istype-void, 
assert_of_bnot, 
firstn_wf, 
length_firstn, 
le_wf, 
decidable_wf, 
iseg_wf, 
primrec-wf2, 
itermAdd_wf, 
int_term_value_add_lemma, 
istype-nat, 
length_wf_nat, 
istype-universe, 
iseg_weakening, 
null_nil_lemma, 
iseg_nil, 
last_wf, 
cons_wf, 
append_wf, 
iseg_append, 
append_back_nil, 
iseg_append_iff, 
iseg_single, 
length_of_cons_lemma, 
equal_wf, 
list_extensionality, 
length-append, 
select_wf, 
squash_wf, 
true_wf, 
select_append_front, 
select_firstn, 
iff_weakening_equal, 
length_firstn_eq, 
less_than_wf, 
add_functionality_wrt_eq, 
select_append_back, 
nat_wf, 
select-nthtl, 
subtype_rel_list, 
top_wf, 
nth_tl_decomp, 
nth_tl_is_nil, 
minus-add, 
minus-minus, 
add-associates, 
minus-one-mul, 
add-swap, 
add-mul-special, 
add-commutes, 
zero-add, 
zero-mul, 
select0, 
hd_wf, 
istype-false
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation_alt, 
lambdaFormation_alt, 
cut, 
thin, 
introduction, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
setElimination, 
rename, 
productElimination, 
hypothesis, 
hypothesisEquality, 
natural_numberEquality, 
independent_isectElimination, 
approximateComputation, 
independent_functionElimination, 
dependent_pairFormation_alt, 
lambdaEquality_alt, 
int_eqEquality, 
dependent_functionElimination, 
Error :memTop, 
sqequalRule, 
independent_pairFormation, 
universeIsType, 
voidElimination, 
unionElimination, 
applyEquality, 
instantiate, 
cumulativity, 
intEquality, 
inhabitedIsType, 
equalityTransitivity, 
equalitySymmetry, 
applyLambdaEquality, 
dependent_set_memberEquality_alt, 
because_Cache, 
productIsType, 
promote_hyp, 
hypothesis_subsumption, 
imageElimination, 
baseClosed, 
functionIsType, 
equalityIstype, 
functionEquality, 
productEquality, 
setIsType, 
addEquality, 
universeEquality, 
inrFormation_alt, 
inlFormation_alt, 
hyp_replacement, 
imageMemberEquality, 
multiplyEquality
Latex:
\mforall{}[T:Type].  \mforall{}[P:(T  List)  {}\mrightarrow{}  \mBbbP{}].
    ((\mforall{}L:T  List.  Dec(P[L]))  {}\mRightarrow{}  (\mforall{}L:T  List.  Dec(\mexists{}L':T  List.  (L'  \mleq{}  L  \mwedge{}  P[L']))))
Date html generated:
2020_05_19-PM-09_48_58
Last ObjectModification:
2019_12_31-PM-00_13_48
Theory : list_1
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