Nuprl Lemma : equipollent-nat-decidable-subset
∀P:ℕ ⟶ ℙ. ((∀n:ℕ. Dec(P[n])) 
⇒ (∀m:ℕ. ∃n:ℕ. (P[n] ∧ (m ≤ n))) 
⇒ ℕ ~ {n:ℕ| P[n]} )
Proof
Definitions occuring in Statement : 
equipollent: A ~ B
, 
nat: ℕ
, 
decidable: Dec(P)
, 
prop: ℙ
, 
so_apply: x[s]
, 
le: A ≤ B
, 
all: ∀x:A. B[x]
, 
exists: ∃x:A. B[x]
, 
implies: P 
⇒ Q
, 
and: P ∧ Q
, 
set: {x:A| B[x]} 
, 
function: x:A ⟶ B[x]
Definitions unfolded in proof : 
all: ∀x:A. B[x]
, 
implies: P 
⇒ Q
, 
decidable: Dec(P)
, 
or: P ∨ Q
, 
exists: ∃x:A. B[x]
, 
member: t ∈ T
, 
isl: isl(x)
, 
iff: P 
⇐⇒ Q
, 
and: P ∧ Q
, 
assert: ↑b
, 
ifthenelse: if b then t else f fi 
, 
btrue: tt
, 
bfalse: ff
, 
false: False
, 
uall: ∀[x:A]. B[x]
, 
rev_implies: P 
⇐ Q
, 
true: True
, 
not: ¬A
, 
so_apply: x[s]
, 
subtype_rel: A ⊆r B
, 
nat: ℕ
, 
prop: ℙ
, 
equipollent: A ~ B
, 
uimplies: b supposing a
, 
so_lambda: λ2x.t[x]
, 
biject: Bij(A;B;f)
, 
inject: Inj(A;B;f)
, 
surject: Surj(A;B;f)
, 
sq_type: SQType(T)
, 
guard: {T}
, 
ge: i ≥ j 
, 
less_than: a < b
, 
squash: ↓T
, 
satisfiable_int_formula: satisfiable_int_formula(fmla)
, 
le: A ≤ B
, 
less_than': less_than'(a;b)
, 
bool-size: 𝔹size(k;f)
, 
enumerate: enumerate(P;n)
, 
subtract: n - m
, 
bool: 𝔹
, 
unit: Unit
, 
it: ⋅
, 
uiff: uiff(P;Q)
, 
int_seg: {i..j-}
, 
lelt: i ≤ j < k
, 
bnot: ¬bb
, 
cand: A c∧ B
, 
has-value: (a)↓
, 
sq_stable: SqStable(P)
Lemmas referenced : 
btrue_wf, 
bfalse_wf, 
istype-nat, 
istype-true, 
istype-void, 
istype-assert, 
istype-le, 
subtype_rel_self, 
decidable_wf, 
enumerate_wf, 
subtype_rel_sets_simple, 
nat_wf, 
assert_wf, 
set_subtype_base, 
le_wf, 
istype-int, 
int_subtype_base, 
biject_wf, 
decidable__lt, 
enumerate-increases, 
subtype_base_sq, 
nat_properties, 
decidable__equal_nat, 
full-omega-unsat, 
intformless_wf, 
itermVar_wf, 
int_formula_prop_less_lemma, 
int_term_value_var_lemma, 
int_formula_prop_wf, 
decidable__equal_int, 
intformand_wf, 
intformnot_wf, 
intformeq_wf, 
int_formula_prop_and_lemma, 
int_formula_prop_not_lemma, 
int_formula_prop_eq_lemma, 
decidable__le, 
intformle_wf, 
itermConstant_wf, 
int_formula_prop_le_lemma, 
int_term_value_constant_lemma, 
decidable__assert, 
bool-size_wf, 
subtype_rel_function, 
bool_wf, 
int_seg_wf, 
int_seg_subtype_nat, 
istype-false, 
ge_wf, 
istype-less_than, 
subtract-1-ge-0, 
primrec0_lemma, 
zero-add, 
mu_wf, 
itermAdd_wf, 
int_term_value_add_lemma, 
squash_wf, 
subtract_wf, 
itermSubtract_wf, 
int_term_value_subtract_lemma, 
minus-one-mul, 
add-commutes, 
add-associates, 
add-mul-special, 
zero-mul, 
primrec-unroll, 
lt_int_wf, 
uiff_transitivity, 
equal-wf-base, 
less_than_wf, 
eqtt_to_assert, 
assert_of_lt_int, 
le_int_wf, 
bnot_wf, 
eqff_to_assert, 
assert_functionality_wrt_uiff, 
bnot_of_lt_int, 
assert_of_le_int, 
equal-wf-T-base, 
not_wf, 
assert_of_bnot, 
int_seg_properties, 
add-is-int-iff, 
false_wf, 
mu-unroll, 
bool_cases_sqequal, 
bool_subtype_base, 
assert-bnot, 
add-zero, 
assert_elim, 
not_assert_elim, 
btrue_neq_bfalse, 
value-type-has-value, 
int-value-type, 
add-swap, 
equal_wf, 
true_wf, 
istype-universe, 
add_nat_wf, 
bool_cases, 
sq_stable__assert
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
lambdaFormation_alt, 
cut, 
rename, 
sqequalHypSubstitution, 
sqequalRule, 
dependent_pairFormation_alt, 
lambdaEquality_alt, 
applyEquality, 
hypothesisEquality, 
inhabitedIsType, 
hypothesis, 
thin, 
unionElimination, 
introduction, 
extract_by_obid, 
equalityIstype, 
equalityTransitivity, 
equalitySymmetry, 
dependent_functionElimination, 
independent_functionElimination, 
independent_pairFormation, 
voidElimination, 
isectElimination, 
because_Cache, 
natural_numberEquality, 
universeIsType, 
functionIsType, 
productIsType, 
productElimination, 
promote_hyp, 
setElimination, 
instantiate, 
universeEquality, 
independent_isectElimination, 
setIsType, 
intEquality, 
sqequalBase, 
setEquality, 
cumulativity, 
imageElimination, 
approximateComputation, 
int_eqEquality, 
Error :memTop, 
dependent_set_memberEquality_alt, 
addEquality, 
intWeakElimination, 
axiomEquality, 
functionIsTypeImplies, 
productEquality, 
functionExtensionality_alt, 
imageMemberEquality, 
baseClosed, 
equalityElimination, 
baseApply, 
closedConclusion, 
applyLambdaEquality, 
pointwiseFunctionality, 
minusEquality, 
callbyvalueReduce, 
hyp_replacement, 
functionEquality
Latex:
\mforall{}P:\mBbbN{}  {}\mrightarrow{}  \mBbbP{}.  ((\mforall{}n:\mBbbN{}.  Dec(P[n]))  {}\mRightarrow{}  (\mforall{}m:\mBbbN{}.  \mexists{}n:\mBbbN{}.  (P[n]  \mwedge{}  (m  \mleq{}  n)))  {}\mRightarrow{}  \mBbbN{}  \msim{}  \{n:\mBbbN{}|  P[n]\}  )
Date html generated:
2020_05_20-AM-08_11_08
Last ObjectModification:
2020_01_04-PM-11_12_30
Theory : general
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