Nuprl Lemma : adjacent-append

∀[T:Type]
  ∀x,y:T. ∀L1,L2:T List.
    (adjacent(T;L1 @ L2;x;y)
    ⇐⇒ adjacent(T;L1;x;y) ∨ (0 < ||L1|| ∧ 0 < ||L2|| ∧ (x = last(L1) ∈ T) ∧ (y = hd(L2) ∈ T)) ∨ adjacent(T;L2;x;y))


Proof




Definitions occuring in Statement :  adjacent: adjacent(T;L;x;y),  last: last(L),  length: ||as||,  append: as @ bs,  hd: hd(l),  list: T List,  less_than: a < b,  uall: ∀[x:A]. B[x],  all: ∀x:A. B[x],  iff: P ⇐⇒ Q,  or: P ∨ Q,  and: P ∧ Q,  natural_number: $n,  universe: Type,  equal: s = t ∈ T
Definitions unfolded in proof :  adjacent: adjacent(T;L;x;y),  uall: ∀[x:A]. B[x],  all: ∀x:A. B[x],  iff: P ⇐⇒ Q,  and: P ∧ Q,  implies: P ⇒ Q,  exists: ∃x:A. B[x],  member: t ∈ T,  int_seg: {i..j-},  uimplies: b supposing a,  top: Top,  guard: {T},  lelt: i ≤ j < k,  decidable: Dec(P),  or: P ∨ Q,  not: ¬A,  satisfiable_int_formula: satisfiable_int_formula(fmla),  false: False,  prop: ℙ,  less_than: a < b,  squash: ↓T,  uiff: uiff(P;Q),  rev_implies: P ⇐ Q,  assert: ↑b,  ifthenelse: if b then t else f fi ,  btrue: tt,  less_than': less_than'(a;b),  cons: [a / b],  bfalse: ff,  ge: i ≥ j ,  subtract: n - m,  append: as @ bs,  so_lambda: so_lambda(x,y,z.t[x; y; z]),  so_apply: x[s1;s2;s3],  true: True,  subtype_rel: A ⊆r B,  cand: A c∧ B,  le: A ≤ B,  last: last(L),  select: L[n],  nil: [],  it: ⋅,  so_lambda: λ2x y.t[x; y],  so_apply: x[s1;s2],  sq_type: SQType(T)
Lemmas referenced :  int_seg_wf,  subtract_wf,  length_wf,  append_wf,  select_wf,  length-append,  istype-void,  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,  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,  subtract-is-int-iff,  add-is-int-iff,  intformless_wf,  itermAdd_wf,  itermSubtract_wf,  int_formula_prop_less_lemma,  int_term_value_add_lemma,  int_term_value_subtract_lemma,  false_wf,  istype-less_than,  last_wf,  list-cases,  null_nil_lemma,  length_of_nil_lemma,  product_subtype_list,  null_cons_lemma,  length_of_cons_lemma,  hd_wf,  list_wf,  istype-universe,  list_ind_nil_lemma,  equal_wf,  squash_wf,  true_wf,  select_append_front,  istype-le,  subtype_rel_self,  iff_weakening_equal,  add-member-int_seg2,  select_append_back,  non_neg_length,  length_append,  subtype_rel_list,  top_wf,  le_wf,  less_than_wf,  decidable__equal_int,  intformeq_wf,  int_formula_prop_eq_lemma,  stuck-spread,  istype-base,  subtype_base_sq,  int_subtype_base,  reduce_hd_cons_lemma,  general_arith_equation1,  add-associates,  add-swap,  add-commutes,  zero-add,  select-nthtl,  length_wf_nat,  nth_tl_append,  add-member-int_seg1,  minus-one-mul,  add-mul-special,  zero-mul,  add-zero
Rules used in proof :  sqequalSubstitution,  sqequalRule,  sqequalReflexivity,  sqequalTransitivity,  computationStep,  isect_memberFormation_alt,  lambdaFormation_alt,  independent_pairFormation,  sqequalHypSubstitution,  productElimination,  thin,  productIsType,  universeIsType,  cut,  introduction,  extract_by_obid,  isectElimination,  natural_numberEquality,  hypothesisEquality,  hypothesis,  equalityIsType1,  inhabitedIsType,  because_Cache,  setElimination,  rename,  independent_isectElimination,  isect_memberEquality_alt,  voidElimination,  addEquality,  dependent_functionElimination,  unionElimination,  approximateComputation,  independent_functionElimination,  dependent_pairFormation_alt,  lambdaEquality_alt,  int_eqEquality,  pointwiseFunctionality,  equalityTransitivity,  equalitySymmetry,  promote_hyp,  imageElimination,  baseApply,  closedConclusion,  baseClosed,  unionIsType,  hypothesis_subsumption,  instantiate,  universeEquality,  inlFormation_alt,  applyEquality,  dependent_set_memberEquality_alt,  imageMemberEquality,  minusEquality,  inrFormation_alt,  productEquality,  hyp_replacement,  applyLambdaEquality,  cumulativity,  intEquality

Latex:
\mforall{}[T:Type]
    \mforall{}x,y:T.  \mforall{}L1,L2:T  List.
        (adjacent(T;L1  @  L2;x;y)
        \mLeftarrow{}{}\mRightarrow{}  adjacent(T;L1;x;y)
                \mvee{}  (0  <  ||L1||  \mwedge{}  0  <  ||L2||  \mwedge{}  (x  =  last(L1))  \mwedge{}  (y  =  hd(L2)))
                \mvee{}  adjacent(T;L2;x;y))



Date html generated: 2019_10_15-AM-11_08_21
Last ObjectModification: 2018_10_18-PM-11_52_15

Theory : general


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