Nuprl Lemma : combine-list-member
∀[T:Type]
  ∀f:T ⟶ T ⟶ T. ∀L:T List.
    ((∀x,y:T.  ((f[x;y] = x ∈ T) ∨ (f[x;y] = y ∈ T))) 
⇒ 0 < ||L|| 
⇒ (combine-list(x,y.f[x;y];L) ∈ L))
Proof
Definitions occuring in Statement : 
combine-list: combine-list(x,y.f[x; y];L)
, 
l_member: (x ∈ l)
, 
length: ||as||
, 
list: T List
, 
less_than: a < b
, 
uall: ∀[x:A]. B[x]
, 
so_apply: x[s1;s2]
, 
all: ∀x:A. B[x]
, 
implies: P 
⇒ Q
, 
or: P ∨ Q
, 
function: x:A ⟶ B[x]
, 
natural_number: $n
, 
universe: Type
, 
equal: s = t ∈ T
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x]
, 
all: ∀x:A. B[x]
, 
implies: P 
⇒ Q
, 
member: t ∈ T
, 
or: P ∨ Q
, 
less_than: a < b
, 
squash: ↓T
, 
less_than': less_than'(a;b)
, 
false: False
, 
and: P ∧ Q
, 
cons: [a / b]
, 
top: Top
, 
combine-list: combine-list(x,y.f[x; y];L)
, 
so_lambda: λ2x.t[x]
, 
so_lambda: λ2x y.t[x; y]
, 
so_apply: x[s1;s2]
, 
so_apply: x[s]
, 
iff: P 
⇐⇒ Q
, 
rev_implies: P 
⇐ Q
, 
prop: ℙ
, 
guard: {T}
Lemmas referenced : 
list-cases, 
length_of_nil_lemma, 
product_subtype_list, 
length_of_cons_lemma, 
reduce_hd_cons_lemma, 
reduce_tl_cons_lemma, 
list_induction, 
all_wf, 
l_member_wf, 
list_accum_wf, 
cons_wf, 
list_wf, 
list_accum_nil_lemma, 
list_accum_cons_lemma, 
cons_member, 
equal_wf, 
less_than_wf, 
length_wf, 
or_wf, 
member_wf, 
member_singleton
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation, 
lambdaFormation, 
cut, 
hypothesisEquality, 
introduction, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
thin, 
hypothesis, 
dependent_functionElimination, 
unionElimination, 
sqequalRule, 
imageElimination, 
productElimination, 
voidElimination, 
promote_hyp, 
hypothesis_subsumption, 
isect_memberEquality, 
voidEquality, 
lambdaEquality, 
cumulativity, 
applyEquality, 
functionExtensionality, 
independent_functionElimination, 
rename, 
because_Cache, 
hyp_replacement, 
equalitySymmetry, 
Error :applyLambdaEquality, 
inrFormation, 
natural_numberEquality, 
functionEquality, 
universeEquality, 
addLevel, 
allFunctionality, 
inlFormation, 
orFunctionality
Latex:
\mforall{}[T:Type]
    \mforall{}f:T  {}\mrightarrow{}  T  {}\mrightarrow{}  T.  \mforall{}L:T  List.
        ((\mforall{}x,y:T.    ((f[x;y]  =  x)  \mvee{}  (f[x;y]  =  y)))  {}\mRightarrow{}  0  <  ||L||  {}\mRightarrow{}  (combine-list(x,y.f[x;y];L)  \mmember{}  L))
Date html generated:
2016_10_21-AM-09_49_46
Last ObjectModification:
2016_07_12-AM-05_09_20
Theory : list_0
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