Nuprl Lemma : bexists_iff_exists_nth

s:DSet. ∀f:|s| ⟶ 𝔹. ∀as:|s| List.  (↑∃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: List int_seg: {i..j-} assert: b bool: 𝔹 so_apply: x[s] all: x:A. B[x] exists: x:A. B[x] iff: ⇐⇒ 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 ⊆B so_apply: x[s] int_seg: {i..j-} uimplies: supposing a guard: {T} lelt: i ≤ j < k and: P ∧ Q decidable: Dec(P) or: P ∨ Q not: ¬A implies:  Q satisfiable_int_formula: satisfiable_int_formula(fmla) exists: x:A. B[x] false: False top: Top prop: less_than: a < b squash: T select: L[n] nil: [] it: so_lambda: λ2y.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 then else fi  bfalse: ff grp_op: * infix_ap: y iff: ⇐⇒ Q rev_implies:  Q ge: i ≥  le: A ≤ B less_than': less_than'(a;b) nat_plus: + true: True uiff: uiff(P;Q) rev_uimplies: rev_uimplies(P;Q) subtract: 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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