Nuprl Lemma : combine-list-as-reduce
∀[A:Type]. ∀[f:A ⟶ A ⟶ A].
  (∀[L:A List]
     combine-list(x,y.f[x;y];L) = outl(reduce(λx,y. case y of inl(z) => inl f[x;z] | inr(z) => inl x;inr ⋅ L)) ∈ A 
     supposing 0 < ||L||) 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)
, 
length: ||as||
, 
reduce: reduce(f;k;as)
, 
list: T List
, 
comm: Comm(T;op)
, 
assoc: Assoc(T;op)
, 
outl: outl(x)
, 
less_than: a < b
, 
it: ⋅
, 
uimplies: b supposing a
, 
uall: ∀[x:A]. B[x]
, 
so_apply: x[s1;s2]
, 
lambda: λx.A[x]
, 
function: x:A ⟶ B[x]
, 
decide: case b of inl(x) => s[x] | inr(y) => t[y]
, 
inr: inr x 
, 
inl: inl x
, 
natural_number: $n
, 
universe: Type
, 
equal: s = t ∈ T
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x]
, 
member: t ∈ T
, 
uimplies: b supposing a
, 
all: ∀x:A. B[x]
, 
or: P ∨ Q
, 
assert: ↑b
, 
ifthenelse: if b then t else f fi 
, 
btrue: tt
, 
less_than: a < b
, 
squash: ↓T
, 
less_than': less_than'(a;b)
, 
false: False
, 
and: P ∧ Q
, 
cons: [a / b]
, 
top: Top
, 
bfalse: ff
, 
not: ¬A
, 
implies: P 
⇒ Q
, 
prop: ℙ
, 
exists: ∃x:A. B[x]
, 
nat: ℕ
, 
ge: i ≥ j 
, 
satisfiable_int_formula: satisfiable_int_formula(fmla)
, 
subtype_rel: A ⊆r B
, 
isl: isl(x)
, 
colength: colength(L)
, 
so_lambda: λ2x y.t[x; y]
, 
so_apply: x[s1;s2]
, 
guard: {T}
, 
decidable: Dec(P)
, 
nil: []
, 
it: ⋅
, 
so_lambda: λ2x.t[x]
, 
so_apply: x[s]
, 
sq_type: SQType(T)
, 
nat_plus: ℕ+
, 
true: True
, 
uiff: uiff(P;Q)
, 
iff: P 
⇐⇒ Q
, 
rev_implies: P 
⇐ Q
, 
append: as @ bs
, 
so_lambda: so_lambda(x,y,z.t[x; y; z])
, 
so_apply: x[s1;s2;s3]
, 
outl: outl(x)
, 
le: A ≤ B
, 
combine-list: combine-list(x,y.f[x; y];L)
, 
comm: Comm(T;op)
, 
infix_ap: x f y
Lemmas referenced : 
last_lemma, 
list-cases, 
null_nil_lemma, 
length_of_nil_lemma, 
product_subtype_list, 
null_cons_lemma, 
length_of_cons_lemma, 
false_wf, 
nat_properties, 
full-omega-unsat, 
intformand_wf, 
intformle_wf, 
itermConstant_wf, 
itermVar_wf, 
intformless_wf, 
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, 
less_than_wf, 
length_wf, 
equal-wf-T-base, 
nat_wf, 
colength_wf_list, 
int_subtype_base, 
reduce_nil_lemma, 
spread_cons_lemma, 
intformeq_wf, 
itermAdd_wf, 
int_formula_prop_eq_lemma, 
int_term_value_add_lemma, 
decidable__le, 
intformnot_wf, 
int_formula_prop_not_lemma, 
le_wf, 
equal_wf, 
subtract_wf, 
itermSubtract_wf, 
int_term_value_subtract_lemma, 
subtype_base_sq, 
set_subtype_base, 
decidable__equal_int, 
reduce_cons_lemma, 
bool_wf, 
bool_subtype_base, 
reduce_wf, 
unit_wf2, 
it_wf, 
btrue_wf, 
list_wf, 
comm_wf, 
assoc_wf, 
last_wf, 
append_wf, 
cons_wf, 
nil_wf, 
length-append, 
add_nat_plus, 
length_wf_nat, 
nat_plus_wf, 
nat_plus_properties, 
decidable__lt, 
add-is-int-iff, 
outl_wf, 
assert_of_tt, 
squash_wf, 
true_wf, 
combine-list-append, 
subtype_rel_self, 
iff_weakening_equal, 
list_ind_cons_lemma, 
list_ind_nil_lemma, 
combine-list_wf, 
non_neg_length, 
assert_wf, 
isl_wf, 
list_induction, 
reduce_hd_cons_lemma, 
reduce_tl_cons_lemma, 
list_accum_nil_lemma, 
list_accum_cons_lemma, 
list_accum_wf, 
combine-list-cons, 
and_wf
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation, 
introduction, 
cut, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
thin, 
hypothesisEquality, 
dependent_functionElimination, 
independent_isectElimination, 
hypothesis, 
unionElimination, 
sqequalRule, 
imageElimination, 
productElimination, 
voidElimination, 
promote_hyp, 
hypothesis_subsumption, 
isect_memberEquality, 
voidEquality, 
lambdaFormation, 
setElimination, 
rename, 
intWeakElimination, 
natural_numberEquality, 
approximateComputation, 
independent_functionElimination, 
dependent_pairFormation, 
lambdaEquality, 
int_eqEquality, 
intEquality, 
independent_pairFormation, 
axiomSqEquality, 
applyEquality, 
because_Cache, 
equalityTransitivity, 
equalitySymmetry, 
applyLambdaEquality, 
dependent_set_memberEquality, 
addEquality, 
baseClosed, 
instantiate, 
cumulativity, 
unionEquality, 
inlEquality, 
inrEquality, 
axiomEquality, 
functionEquality, 
universeEquality, 
hyp_replacement, 
imageMemberEquality, 
pointwiseFunctionality, 
baseApply, 
closedConclusion, 
functionExtensionality
Latex:
\mforall{}[A:Type].  \mforall{}[f:A  {}\mrightarrow{}  A  {}\mrightarrow{}  A].
    (\mforall{}[L:A  List]
          combine-list(x,y.f[x;y];L)
          =  outl(reduce(\mlambda{}x,y.  case  y  of  inl(z)  =>  inl  f[x;z]  |  inr(z)  =>  inl  x;inr  \mcdot{}  ;L)) 
          supposing  0  <  ||L||)  supposing 
          (Comm(A;\mlambda{}x,y.  f[x;y])  and 
          Assoc(A;\mlambda{}x,y.  f[x;y]))
Date html generated:
2019_06_20-PM-01_30_30
Last ObjectModification:
2018_08_21-PM-01_55_59
Theory : list_1
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