Nuprl Lemma : simple_general_fan_theorem

∀[T:Type]
  (Bounded(T)
  ⇒ (∀[X:n:ℕ ⟶ (ℕn ⟶ T) ⟶ ℙ]
        (∀n:ℕ. ∀s:ℕn ⟶ T.  Dec(X[n;s])) ⇒ (∃k:ℕ [(∀f:ℕ ⟶ T. ∃n:ℕk. X[n;f])]) supposing ∀f:ℕ ⟶ T. (↓∃n:ℕ. X[n;f])))


Proof




Definitions occuring in Statement :  bounded-type: Bounded(T),  int_seg: {i..j-},  nat: ℕ,  decidable: Dec(P),  uimplies: b supposing a,  uall: ∀[x:A]. B[x],  prop: ℙ,  so_apply: x[s1;s2],  all: ∀x:A. B[x],  sq_exists: ∃x:A [B[x]],  exists: ∃x:A. B[x],  squash: ↓T,  implies: P ⇒ Q,  function: x:A ⟶ B[x],  natural_number: $n,  universe: Type
Definitions unfolded in proof :  nat_plus: ℕ+,  ge: i ≥ j ,  seq-adjoin: s++t,  assert: ↑b,  ifthenelse: if b then t else f fi ,  bnot: ¬bb,  bfalse: ff,  cand: A c∧ B,  btrue: tt,  it: ⋅,  unit: Unit,  bool: 𝔹,  seq-append: seq-append(n;m;s1;s2),  istype: istype(T),  sq_type: SQType(T),  less_than: a < b,  true: True,  top: Top,  subtract: n - m,  uiff: uiff(P;Q),  rev_implies: P ⇐ Q,  iff: P ⇐⇒ Q,  or: P ∨ Q,  decidable: Dec(P),  exists: ∃x:A. B[x],  sq_exists: ∃x:A [B[x]],  prop: ℙ,  so_apply: x[s],  not: ¬A,  false: False,  less_than': less_than'(a;b),  subtype_rel: A ⊆r B,  le: A ≤ B,  and: P ∧ Q,  lelt: i ≤ j < k,  sq_stable: SqStable(P),  guard: {T},  int_seg: {i..j-},  so_apply: x[s1;s2],  nat: ℕ,  so_lambda: λ2x.t[x],  so_lambda: λ2x y.t[x; y],  squash: ↓T,  all: ∀x:A. B[x],  member: t ∈ T,  uimplies: b supposing a,  implies: P ⇒ Q,  uall: ∀[x:A]. B[x],  bounded-type: Bounded(T)
Lemmas referenced :  less_than_irreflexivity,  less_than_transitivity1,  not-equal-2,  decidable__int_equal,  nat_properties,  le-add-cancel-alt,  mul-commutes,  mul-associates,  mul-distributes,  omega-shadow,  mul-distributes-right,  two-mul,  zero-mul,  add-mul-special,  one-mul,  minus-zero,  le_reflexive,  and_wf,  add-is-int-iff,  istype-sqequal,  le_weakening2,  minus-minus,  decidable__lt,  le-add-cancel2,  subtract_wf,  add-member-int_seg2,  decidable__exists_int_seg,  sq_stable_from_decidable,  sq_stable__all,  less-iff-le,  not-lt-2,  istype-assert,  assert_of_bnot,  iff_weakening_uiff,  less_than_wf,  not_wf,  bnot_wf,  assert_wf,  iff_transitivity,  bool_subtype_base,  bool_wf,  bool_cases_sqequal,  eqff_to_assert,  istype-top,  assert_of_lt_int,  eqtt_to_assert,  lt_int_wf,  int_subtype_base,  istype-int,  le_wf,  set_subtype_base,  subtype_base_sq,  subtype_rel_dep_function,  istype-less_than,  istype-universe,  squash_wf,  decidable_wf,  istype-nat,  seq-adjoin_wf,  le-add-cancel,  add-zero,  add_functionality_wrt_le,  add-commutes,  add-swap,  add-associates,  minus-one-mul-top,  zero-add,  minus-one-mul,  minus-add,  condition-implies-le,  not-le-2,  decidable__le,  istype-void,  subtype_rel_self,  subtype_rel_function,  istype-false,  int_seg_subtype_nat,  seq-append_wf,  istype-le,  sq_stable__le,  add_nat_wf,  int_seg_wf,  exists_wf,  all_wf,  nat_wf,  sq_exists_wf,  basic_bar_induction
Rules used in proof :  baseApply,  multiplyEquality,  functionExtensionality,  promote_hyp,  isectIsTypeImplies,  axiomSqEquality,  lessCases,  equalityElimination,  functionExtensionality_alt,  intEquality,  cumulativity,  hyp_replacement,  dependent_pairFormation_alt,  dependent_set_memberFormation_alt,  universeEquality,  productEquality,  minusEquality,  isect_memberEquality_alt,  unionElimination,  voidElimination,  productIsType,  setIsType,  instantiate,  functionIsType,  universeIsType,  independent_pairFormation,  independent_isectElimination,  equalitySymmetry,  equalityTransitivity,  equalityIstype,  productElimination,  independent_functionElimination,  addEquality,  dependent_set_memberEquality_alt,  applyEquality,  setElimination,  natural_numberEquality,  closedConclusion,  because_Cache,  functionEquality,  isectElimination,  extract_by_obid,  rename,  inhabitedIsType,  functionIsTypeImplies,  baseClosed,  imageMemberEquality,  hypothesis,  imageElimination,  hypothesisEquality,  thin,  dependent_functionElimination,  lambdaEquality_alt,  sqequalHypSubstitution,  introduction,  cut,  lambdaFormation_alt,  isect_memberFormation_alt,  computationStep,  sqequalTransitivity,  sqequalReflexivity,  sqequalRule,  sqequalSubstitution

Latex:
\mforall{}[T:Type]
    (Bounded(T)
    {}\mRightarrow{}  (\mforall{}[X:n:\mBbbN{}  {}\mrightarrow{}  (\mBbbN{}n  {}\mrightarrow{}  T)  {}\mrightarrow{}  \mBbbP{}]
                (\mforall{}n:\mBbbN{}.  \mforall{}s:\mBbbN{}n  {}\mrightarrow{}  T.    Dec(X[n;s]))  {}\mRightarrow{}  (\mexists{}k:\mBbbN{}  [(\mforall{}f:\mBbbN{}  {}\mrightarrow{}  T.  \mexists{}n:\mBbbN{}k.  X[n;f])]) 
                supposing  \mforall{}f:\mBbbN{}  {}\mrightarrow{}  T.  (\mdownarrow{}\mexists{}n:\mBbbN{}.  X[n;f])))



Date html generated: 2019_10_15-AM-10_20_24
Last ObjectModification: 2019_10_07-PM-04_44_24

Theory : bar-induction


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