Nuprl Lemma : select-front-as-reduce

∀[n:ℕ]. ∀[L:Top List].
  L[n] ~ hd(reduce(λu,x. if ||x|| <z n + 1 then x @ [u] else tl(x) @ [u] fi ;[];L)) supposing n < ||L||


Proof




Definitions occuring in Statement :  select: L[n],  hd: hd(l),  length: ||as||,  append: as @ bs,  reduce: reduce(f;k;as),  tl: tl(l),  cons: [a / b],  nil: [],  list: T List,  nat: ℕ,  ifthenelse: if b then t else f fi ,  lt_int: i <z j,  less_than: a < b,  uimplies: b supposing a,  uall: ∀[x:A]. B[x],  top: Top,  lambda: λx.A[x],  add: n + m,  natural_number: $n,  sqequal: s ~ t
Definitions unfolded in proof :  uall: ∀[x:A]. B[x],  member: t ∈ T,  all: ∀x:A. B[x],  nat: ℕ,  implies: P ⇒ Q,  false: False,  ge: i ≥ j ,  uimplies: b supposing a,  satisfiable_int_formula: satisfiable_int_formula(fmla),  exists: ∃x:A. B[x],  not: ¬A,  top: Top,  and: P ∧ Q,  prop: ℙ,  subtype_rel: A ⊆r B,  guard: {T},  or: P ∨ Q,  firstn: firstn(n;as),  so_lambda: so_lambda(x,y,z.t[x; y; z]),  so_apply: x[s1;s2;s3],  cons: [a / b],  colength: colength(L),  so_lambda: λ2x y.t[x; y],  so_apply: x[s1;s2],  decidable: Dec(P),  nil: [],  it: ⋅,  so_lambda: λ2x.t[x],  so_apply: x[s],  sq_type: SQType(T),  less_than: a < b,  squash: ↓T,  less_than': less_than'(a;b),  bool: 𝔹,  unit: Unit,  btrue: tt,  uiff: uiff(P;Q),  bfalse: ff,  bnot: ¬bb,  ifthenelse: if b then t else f fi ,  assert: ↑b,  le: A ≤ B,  int_seg: {i..j-},  lelt: i ≤ j < k,  last: last(L),  int_iseg: {i...j},  cand: A c∧ B,  append: as @ bs
Lemmas referenced :  nat_properties,  satisfiable-full-omega-tt,  intformand_wf,  intformle_wf,  itermConstant_wf,  itermVar_wf,  intformless_wf,  int_formula_prop_and_lemma,  int_formula_prop_le_lemma,  int_term_value_constant_lemma,  int_term_value_var_lemma,  int_formula_prop_less_lemma,  int_formula_prop_wf,  ge_wf,  less_than_wf,  equal-wf-T-base,  nat_wf,  colength_wf_list,  top_wf,  less_than_transitivity1,  less_than_irreflexivity,  list-cases,  reduce_nil_lemma,  list_ind_nil_lemma,  reverse_nil_lemma,  product_subtype_list,  spread_cons_lemma,  intformeq_wf,  itermAdd_wf,  int_formula_prop_eq_lemma,  int_term_value_add_lemma,  decidable__le,  intformnot_wf,  int_formula_prop_not_lemma,  le_wf,  equal_wf,  subtract_wf,  itermSubtract_wf,  int_term_value_subtract_lemma,  subtype_base_sq,  set_subtype_base,  int_subtype_base,  decidable__equal_int,  reduce_cons_lemma,  list_wf,  length_wf,  le_int_wf,  bool_wf,  eqtt_to_assert,  assert_of_le_int,  length-reverse,  eqff_to_assert,  bool_cases_sqequal,  bool_subtype_base,  assert-bnot,  lt_int_wf,  firstn_wf,  assert_wf,  bnot_wf,  uiff_transitivity,  assert_of_lt_int,  assert_functionality_wrt_uiff,  bnot_of_lt_int,  cons_wf,  length_of_cons_lemma,  non_neg_length,  reverse-cons,  list_ind_cons_lemma,  append_firstn_lastn_sq,  decidable__lt,  lelt_wf,  reverse-append,  nth_tl_wf,  nth_tl_decomp,  length_nth_tl,  length_of_nil_lemma,  equal-wf-base,  reduce_tl_cons_lemma,  add-subtract-cancel,  length_firstn,  firstn_decomp,  nil_wf,  reduce_hd_cons_lemma,  hd-reverse
Rules used in proof :  sqequalSubstitution,  sqequalTransitivity,  computationStep,  sqequalReflexivity,  isect_memberFormation,  introduction,  cut,  lambdaFormation,  thin,  extract_by_obid,  sqequalHypSubstitution,  isectElimination,  hypothesisEquality,  hypothesis,  setElimination,  rename,  intWeakElimination,  natural_numberEquality,  independent_isectElimination,  dependent_pairFormation,  lambdaEquality,  int_eqEquality,  intEquality,  dependent_functionElimination,  isect_memberEquality,  voidElimination,  voidEquality,  sqequalRule,  independent_pairFormation,  computeAll,  independent_functionElimination,  sqequalAxiom,  applyEquality,  because_Cache,  unionElimination,  promote_hyp,  hypothesis_subsumption,  productElimination,  equalityTransitivity,  equalitySymmetry,  applyLambdaEquality,  dependent_set_memberEquality,  addEquality,  baseClosed,  instantiate,  cumulativity,  imageElimination,  equalityElimination,  productEquality

Latex:
\mforall{}[n:\mBbbN{}].  \mforall{}[L:Top  List].
    L[n]  \msim{}  hd(reduce(\mlambda{}u,x.  if  ||x||  <z  n  +  1  then  x  @  [u]  else  tl(x)  @  [u]  fi  ;[];L))  supposing  n  <  ||\000CL||



Date html generated: 2018_05_21-PM-07_35_29
Last ObjectModification: 2017_07_26-PM-05_09_38

Theory : general


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