Nuprl Lemma : fun-connected-step-back

∀[T:Type]. ∀f:T ⟶ T. ∀x,y:T.  (x is f*(y) ⇒ x is f*(f y) supposing ¬(x = y ∈ T))


Proof




Definitions occuring in Statement :  fun-connected: y is f*(x),  uimplies: b supposing a,  uall: ∀[x:A]. B[x],  all: ∀x:A. B[x],  not: ¬A,  implies: P ⇒ Q,  apply: f a,  function: x:A ⟶ B[x],  universe: Type,  equal: s = t ∈ T
Definitions unfolded in proof :  uall: ∀[x:A]. B[x],  all: ∀x:A. B[x],  implies: P ⇒ Q,  uimplies: b supposing a,  member: t ∈ T,  not: ¬A,  false: False,  fun-connected: y is f*(x),  exists: ∃x:A. B[x],  or: P ∨ Q,  fun-path: y=f*(x) via L,  select: L[n],  nil: [],  it: ⋅,  so_lambda: λ2x y.t[x; y],  so_apply: x[s1;s2],  subtract: n - m,  assert: ↑b,  ifthenelse: if b then t else f fi ,  btrue: tt,  and: P ∧ Q,  less_than: a < b,  squash: ↓T,  less_than': less_than'(a;b),  cons: [a / b],  bfalse: ff,  prop: ℙ,  append: as @ bs,  so_lambda: so_lambda3,  so_apply: x[s1;s2;s3],  ge: i ≥ j ,  true: True,  guard: {T},  nat: ℕ,  le: A ≤ B,  cand: A c∧ B,  decidable: Dec(P),  iff: P ⇐⇒ Q,  rev_implies: P ⇐ Q,  uiff: uiff(P;Q),  listp: A List+,  subtype_rel: A ⊆r B,  satisfiable_int_formula: satisfiable_int_formula(fmla),  int_seg: {i..j-},  lelt: i ≤ j < k,  last: last(L),  sq_type: SQType(T)
Lemmas referenced :  list-cases,  length_of_nil_lemma,  stuck-spread,  istype-base,  null_nil_lemma,  product_subtype_list,  length_of_cons_lemma,  reduce_hd_cons_lemma,  null_cons_lemma,  istype-void,  fun-connected_wf,  istype-universe,  last_lemma,  fun-path_wf,  list_ind_nil_lemma,  last_wf,  hd_wf,  squash_wf,  ge_wf,  length_wf,  list_wf,  listp_properties,  length_wf_nat,  decidable__lt,  istype-false,  not-lt-2,  condition-implies-le,  minus-add,  minus-one-mul,  zero-add,  minus-one-mul-top,  add-commutes,  add_functionality_wrt_le,  add-associates,  add-zero,  le-add-cancel,  istype-less_than,  cons_wf,  nil_wf,  member-less_than,  append_wf,  length_nil,  non_neg_length,  length_cons,  length_append,  subtype_rel_list,  top_wf,  length-append,  full-omega-unsat,  intformand_wf,  intformnot_wf,  intformless_wf,  itermConstant_wf,  itermAdd_wf,  itermVar_wf,  intformle_wf,  istype-int,  int_formula_prop_and_lemma,  int_formula_prop_not_lemma,  int_formula_prop_less_lemma,  int_term_value_constant_lemma,  int_term_value_add_lemma,  int_term_value_var_lemma,  int_formula_prop_le_lemma,  int_formula_prop_wf,  hd-append-sq,  cons-listp,  int_seg_wf,  subtract_wf,  list_ind_cons_lemma,  decidable__le,  add-is-int-iff,  itermSubtract_wf,  int_term_value_subtract_lemma,  false_wf,  istype-le,  equal_wf,  true_wf,  select_wf,  select_append_front,  subtype_rel_self,  iff_weakening_equal,  subtype_base_sq,  int_subtype_base,  general_arith_equation1,  length-singleton,  int_seg_properties,  select-nthtl0,  int_seg_subtype_nat
Rules used in proof :  sqequalSubstitution,  sqequalTransitivity,  computationStep,  sqequalReflexivity,  isect_memberFormation_alt,  lambdaFormation_alt,  cut,  introduction,  sqequalRule,  sqequalHypSubstitution,  lambdaEquality_alt,  dependent_functionElimination,  thin,  hypothesisEquality,  voidElimination,  functionIsTypeImplies,  inhabitedIsType,  rename,  productElimination,  extract_by_obid,  isectElimination,  hypothesis,  unionElimination,  baseClosed,  independent_isectElimination,  Error :memTop,  imageElimination,  promote_hyp,  hypothesis_subsumption,  functionIsType,  equalityIstype,  universeIsType,  because_Cache,  instantiate,  universeEquality,  dependent_pairFormation_alt,  applyEquality,  independent_functionElimination,  equalityTransitivity,  equalitySymmetry,  natural_numberEquality,  setElimination,  independent_pairFormation,  addEquality,  minusEquality,  dependent_set_memberEquality_alt,  imageMemberEquality,  independent_pairEquality,  axiomEquality,  hyp_replacement,  applyLambdaEquality,  voidEquality,  approximateComputation,  int_eqEquality,  pointwiseFunctionality,  baseApply,  closedConclusion,  productIsType,  cumulativity,  intEquality

Latex:
\mforall{}[T:Type].  \mforall{}f:T  {}\mrightarrow{}  T.  \mforall{}x,y:T.    (x  is  f*(y)  {}\mRightarrow{}  x  is  f*(f  y)  supposing  \mneg{}(x  =  y))



Date html generated: 2020_05_20-AM-08_10_38
Last ObjectModification: 2019_12_31-PM-06_30_08

Theory : general


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