Nuprl Lemma : reduce-as-combine-list
∀[A:Type]. ∀[f:A ⟶ A ⟶ A].
  (∀[L:A List]. ∀[z:A].  (reduce(f;z;L) = combine-list(x,y.f[x;y];[z / L]) ∈ A)) supposing 
     (Comm(A;λx,y. f[x;y]) and 
     Assoc(A;λx,y. f[x;y]))
Proof
Definitions occuring in Statement : 
combine-list: combine-list(x,y.f[x; y];L)
, 
reduce: reduce(f;k;as)
, 
cons: [a / b]
, 
list: T List
, 
comm: Comm(T;op)
, 
assoc: Assoc(T;op)
, 
uimplies: b supposing a
, 
uall: ∀[x:A]. B[x]
, 
so_apply: x[s1;s2]
, 
lambda: λx.A[x]
, 
function: x:A ⟶ B[x]
, 
universe: Type
, 
equal: s = t ∈ T
Definitions unfolded in proof : 
so_apply: x[s1;s2]
, 
combine-list: combine-list(x,y.f[x; y];L)
, 
comm: Comm(T;op)
, 
assoc: Assoc(T;op)
, 
infix_ap: x f y
, 
all: ∀x:A. B[x]
, 
member: t ∈ T
, 
uall: ∀[x:A]. B[x]
, 
uimplies: b supposing a
, 
nat: ℕ
, 
implies: P 
⇒ Q
, 
false: False
, 
ge: i ≥ j 
, 
not: ¬A
, 
satisfiable_int_formula: satisfiable_int_formula(fmla)
, 
exists: ∃x:A. B[x]
, 
and: P ∧ Q
, 
prop: ℙ
, 
or: P ∨ Q
, 
so_lambda: λ2x y.t[x; y]
, 
cons: [a / b]
, 
le: A ≤ B
, 
less_than': less_than'(a;b)
, 
colength: colength(L)
, 
nil: []
, 
it: ⋅
, 
guard: {T}
, 
so_lambda: λ2x.t[x]
, 
so_apply: x[s]
, 
sq_type: SQType(T)
, 
less_than: a < b
, 
squash: ↓T
, 
decidable: Dec(P)
, 
subtype_rel: A ⊆r B
, 
true: True
, 
iff: P 
⇐⇒ Q
, 
rev_implies: P 
⇐ Q
Lemmas referenced : 
reduce_hd_cons_lemma, 
reduce_tl_cons_lemma, 
nat_properties, 
full-omega-unsat, 
intformand_wf, 
intformle_wf, 
itermConstant_wf, 
itermVar_wf, 
intformless_wf, 
istype-int, 
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, 
istype-less_than, 
list-cases, 
reduce_nil_lemma, 
list_accum_nil_lemma, 
product_subtype_list, 
colength-cons-not-zero, 
colength_wf_list, 
istype-void, 
istype-le, 
subtract-1-ge-0, 
subtype_base_sq, 
intformeq_wf, 
int_formula_prop_eq_lemma, 
set_subtype_base, 
int_subtype_base, 
spread_cons_lemma, 
decidable__equal_int, 
subtract_wf, 
intformnot_wf, 
itermSubtract_wf, 
itermAdd_wf, 
int_formula_prop_not_lemma, 
int_term_value_subtract_lemma, 
int_term_value_add_lemma, 
decidable__le, 
le_wf, 
reduce_cons_lemma, 
list_accum_cons_lemma, 
equal_wf, 
squash_wf, 
true_wf, 
reduce_wf, 
subtype_rel_self, 
iff_weakening_equal, 
istype-nat, 
list_wf, 
istype-universe
Rules used in proof : 
sqequalSubstitution, 
sqequalRule, 
sqequalReflexivity, 
sqequalTransitivity, 
computationStep, 
cut, 
introduction, 
extract_by_obid, 
sqequalHypSubstitution, 
dependent_functionElimination, 
thin, 
Error :memTop, 
hypothesis, 
isect_memberFormation_alt, 
lambdaFormation_alt, 
isectElimination, 
hypothesisEquality, 
setElimination, 
rename, 
intWeakElimination, 
natural_numberEquality, 
independent_isectElimination, 
approximateComputation, 
independent_functionElimination, 
dependent_pairFormation_alt, 
lambdaEquality_alt, 
int_eqEquality, 
independent_pairFormation, 
universeIsType, 
voidElimination, 
isect_memberEquality_alt, 
axiomEquality, 
isectIsTypeImplies, 
inhabitedIsType, 
functionIsTypeImplies, 
unionElimination, 
because_Cache, 
promote_hyp, 
hypothesis_subsumption, 
productElimination, 
equalityIstype, 
dependent_set_memberEquality_alt, 
instantiate, 
equalityTransitivity, 
equalitySymmetry, 
applyLambdaEquality, 
imageElimination, 
baseApply, 
closedConclusion, 
baseClosed, 
applyEquality, 
intEquality, 
sqequalBase, 
imageMemberEquality, 
isectIsType, 
functionIsType, 
universeEquality, 
hyp_replacement
Latex:
\mforall{}[A:Type].  \mforall{}[f:A  {}\mrightarrow{}  A  {}\mrightarrow{}  A].
    (\mforall{}[L:A  List].  \mforall{}[z:A].    (reduce(f;z;L)  =  combine-list(x,y.f[x;y];[z  /  L])))  supposing 
          (Comm(A;\mlambda{}x,y.  f[x;y])  and 
          Assoc(A;\mlambda{}x,y.  f[x;y]))
Date html generated:
2020_05_19-PM-09_45_07
Last ObjectModification:
2019_12_31-PM-00_13_15
Theory : list_1
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