Nuprl Lemma : remove-repeats-length-no-repeats

[T:Type]. ∀[eq:EqDecider(T)]. ∀[L:T List].  ||remove-repeats(eq;L)|| ||L|| ∈ ℤ supposing no_repeats(T;L)


Proof




Definitions occuring in Statement :  remove-repeats: remove-repeats(eq;L) no_repeats: no_repeats(T;l) length: ||as|| list: List deq: EqDecider(T) uimplies: supposing a uall: [x:A]. B[x] int: universe: Type equal: t ∈ T
Definitions unfolded in proof :  uall: [x:A]. B[x] member: t ∈ T so_lambda: λ2x.t[x] implies:  Q prop: so_apply: x[s] all: x:A. B[x] uimplies: supposing a top: Top uiff: uiff(P;Q) and: P ∧ Q append: as bs so_lambda: so_lambda(x,y,z.t[x; y; z]) so_apply: x[s1;s2;s3] squash: T true: True subtype_rel: A ⊆B guard: {T} iff: ⇐⇒ Q rev_implies:  Q or: P ∨ Q not: ¬A false: False decidable: Dec(P) satisfiable_int_formula: satisfiable_int_formula(fmla) exists: x:A. B[x]
Lemmas referenced :  list_induction no_repeats_wf equal_wf length_wf remove-repeats_wf list_wf deq_wf remove_repeats_nil_lemma length_of_nil_lemma nil_wf no_repeats_cons list_ind_cons_lemma list_ind_nil_lemma squash_wf true_wf remove-repeats-append cons_wf append_wf iff_weakening_equal remove-repeats-append-one-member length-append length_of_cons_lemma decidable__equal_int satisfiable-full-omega-tt intformand_wf intformnot_wf intformeq_wf itermVar_wf itermAdd_wf itermConstant_wf int_formula_prop_and_lemma int_formula_prop_not_lemma int_formula_prop_eq_lemma int_term_value_var_lemma int_term_value_add_lemma int_term_value_constant_lemma int_formula_prop_wf
Rules used in proof :  cut thin introduction extract_by_obid sqequalHypSubstitution sqequalSubstitution sqequalTransitivity computationStep sqequalReflexivity isectElimination hypothesisEquality sqequalRule lambdaEquality functionEquality cumulativity hypothesis intEquality independent_functionElimination lambdaFormation rename because_Cache dependent_functionElimination universeEquality isect_memberFormation isect_memberEquality axiomEquality equalityTransitivity equalitySymmetry voidElimination voidEquality natural_numberEquality productElimination independent_isectElimination applyEquality imageElimination equalityUniverse levelHypothesis imageMemberEquality baseClosed unionElimination dependent_pairFormation int_eqEquality independent_pairFormation computeAll

Latex:
\mforall{}[T:Type].  \mforall{}[eq:EqDecider(T)].  \mforall{}[L:T  List].
    ||remove-repeats(eq;L)||  =  ||L||  supposing  no\_repeats(T;L)



Date html generated: 2017_04_17-AM-09_12_42
Last ObjectModification: 2017_02_27-PM-05_19_39

Theory : decidable!equality


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