Nuprl Lemma : firstn_append_front

∀[L1:Top List]. ∀L2:Top List. (firstn(||L1 @ L2|| - ||L2||;L1 @ L2) ~ L1)


Proof




Definitions occuring in Statement :  firstn: firstn(n;as),  length: ||as||,  append: as @ bs,  list: T List,  uall: ∀[x:A]. B[x],  top: Top,  all: ∀x:A. B[x],  subtract: n - m,  sqequal: s ~ t
Definitions unfolded in proof :  uall: ∀[x:A]. B[x],  member: t ∈ T,  all: ∀x:A. B[x],  int_seg: {i..j-},  lelt: i ≤ j < k,  and: P ∧ Q,  squash: ↓T,  prop: ℙ,  true: True,  subtype_rel: A ⊆r B,  uimplies: b supposing a,  guard: {T},  iff: P ⇐⇒ Q,  rev_implies: P ⇐ Q,  implies: P ⇒ Q,  ge: i ≥ j ,  decidable: Dec(P),  or: P ∨ Q,  le: A ≤ B,  satisfiable_int_formula: satisfiable_int_formula(fmla),  exists: ∃x:A. B[x],  false: False,  not: ¬A,  top: Top
Lemmas referenced :  firstn_all,  add-subtract-cancel,  lelt_wf,  int_formula_prop_less_lemma,  intformless_wf,  decidable__lt,  length-append,  int_formula_prop_wf,  int_term_value_var_lemma,  int_term_value_add_lemma,  int_term_value_subtract_lemma,  int_term_value_constant_lemma,  int_formula_prop_le_lemma,  int_formula_prop_not_lemma,  int_formula_prop_and_lemma,  itermVar_wf,  itermAdd_wf,  itermSubtract_wf,  itermConstant_wf,  intformle_wf,  intformnot_wf,  intformand_wf,  satisfiable-full-omega-tt,  decidable__le,  non_neg_length,  iff_weakening_equal,  length_append,  true_wf,  squash_wf,  le_wf,  append_wf,  length_wf,  subtract_wf,  firstn_append,  top_wf,  list_wf
Rules used in proof :  sqequalSubstitution,  sqequalTransitivity,  computationStep,  sqequalReflexivity,  isect_memberFormation,  introduction,  cut,  lambdaFormation,  hypothesis,  lemma_by_obid,  sqequalHypSubstitution,  isectElimination,  thin,  sqequalRule,  lambdaEquality,  dependent_functionElimination,  hypothesisEquality,  sqequalAxiom,  because_Cache,  dependent_set_memberEquality,  independent_pairFormation,  applyEquality,  imageElimination,  equalityTransitivity,  equalitySymmetry,  intEquality,  natural_numberEquality,  imageMemberEquality,  baseClosed,  universeEquality,  independent_isectElimination,  productElimination,  independent_functionElimination,  unionElimination,  dependent_pairFormation,  int_eqEquality,  isect_memberEquality,  voidElimination,  voidEquality,  computeAll,  addEquality

Latex:
\mforall{}[L1:Top  List].  \mforall{}L2:Top  List.  (firstn(||L1  @  L2||  -  ||L2||;L1  @  L2)  \msim{}  L1)



Date html generated: 2016_05_14-PM-02_08_24
Last ObjectModification: 2016_01_15-AM-08_02_20

Theory : list_1


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