Nuprl Lemma : select_firstn
∀[T:Type]. ∀[as:T List]. ∀[n:{0...||as||}]. ∀[i:ℕn].  (firstn(n;as)[i] = as[i] ∈ T)
Proof
Definitions occuring in Statement : 
firstn: firstn(n;as)
, 
select: L[n]
, 
length: ||as||
, 
list: T List
, 
int_iseg: {i...j}
, 
int_seg: {i..j-}
, 
uall: ∀[x:A]. B[x]
, 
natural_number: $n
, 
universe: Type
, 
equal: s = t ∈ T
Definitions unfolded in proof : 
true: True
, 
less_than': less_than'(a;b)
, 
le: A ≤ B
, 
top: Top
, 
subtract: n - m
, 
squash: ↓T
, 
lelt: i ≤ j < k
, 
sq_stable: SqStable(P)
, 
uiff: uiff(P;Q)
, 
false: False
, 
rev_implies: P 
⇐ Q
, 
not: ¬A
, 
iff: P 
⇐⇒ Q
, 
or: P ∨ Q
, 
decidable: Dec(P)
, 
int_seg: {i..j-}
, 
cand: A c∧ B
, 
implies: P 
⇒ Q
, 
all: ∀x:A. B[x]
, 
uimplies: b supposing a
, 
so_apply: x[s]
, 
and: P ∧ Q
, 
prop: ℙ
, 
so_lambda: λ2x.t[x]
, 
uall: ∀[x:A]. B[x]
, 
nat: ℕ
, 
int_iseg: {i...j}
, 
subtype_rel: A ⊆r B
, 
member: t ∈ T
, 
guard: {T}
, 
less_than: a < b
, 
firstn: firstn(n;as)
, 
bool: 𝔹
, 
unit: Unit
, 
it: ⋅
, 
btrue: tt
, 
ifthenelse: if b then t else f fi 
, 
bfalse: ff
, 
so_lambda: so_lambda(x,y,z.t[x; y; z])
, 
so_apply: x[s1;s2;s3]
, 
select: L[n]
, 
nil: []
, 
so_lambda: λ2x y.t[x; y]
, 
so_apply: x[s1;s2]
, 
cons: [a / b]
Lemmas referenced : 
list_wf, 
int_iseg_wf, 
int_seg_wf, 
le-add-cancel, 
add-associates, 
add_functionality_wrt_le, 
add-commutes, 
minus-one-mul-top, 
add-swap, 
minus-one-mul, 
minus-add, 
condition-implies-le, 
sq_stable__le, 
not-le-2, 
false_wf, 
decidable__le, 
length_wf, 
le_wf, 
subtype_rel_sets, 
nat_wf, 
subtract_wf, 
istype-universe, 
select_wf, 
firstn_wf, 
less_than_wf, 
squash_wf, 
true_wf, 
istype-int, 
length_firstn_eq, 
istype-false, 
less-iff-le, 
zero-add, 
istype-void, 
minus-minus, 
add-zero, 
subtype_rel_self, 
iff_weakening_equal, 
less_than_transitivity1, 
primrec-wf2, 
all_wf, 
equal_wf, 
lt_int_wf, 
equal-wf-base, 
bool_wf, 
assert_wf, 
le_int_wf, 
bnot_wf, 
less_than_irreflexivity, 
int_subtype_base, 
uiff_transitivity, 
eqtt_to_assert, 
assert_of_lt_int, 
eqff_to_assert, 
assert_functionality_wrt_uiff, 
bnot_of_lt_int, 
assert_of_le_int, 
list-cases, 
length_of_nil_lemma, 
list_ind_nil_lemma, 
stuck-spread, 
istype-base, 
product_subtype_list, 
length_of_cons_lemma, 
list_ind_cons_lemma, 
decidable__equal_int, 
le_weakening, 
select_cons_hd, 
decidable__lt, 
not-lt-2, 
not-equal-2, 
minus-zero, 
le-add-cancel2, 
select_cons_tl, 
le-add-cancel-alt
Rules used in proof : 
axiomEquality, 
isect_memberFormation, 
universeEquality, 
minusEquality, 
voidEquality, 
isect_memberEquality, 
addEquality, 
imageElimination, 
baseClosed, 
imageMemberEquality, 
independent_functionElimination, 
voidElimination, 
independent_pairFormation, 
unionElimination, 
dependent_functionElimination, 
productElimination, 
lambdaFormation, 
setEquality, 
rename, 
setElimination, 
independent_isectElimination, 
cumulativity, 
hypothesis, 
natural_numberEquality, 
productEquality, 
lambdaEquality, 
because_Cache, 
intEquality, 
thin, 
isectElimination, 
sqequalHypSubstitution, 
extract_by_obid, 
introduction, 
sqequalRule, 
applyEquality, 
hypothesisEquality, 
sqequalReflexivity, 
computationStep, 
sqequalTransitivity, 
sqequalSubstitution, 
cut, 
Error :lambdaFormation_alt, 
Error :universeIsType, 
Error :functionIsType, 
Error :equalityIsType1, 
Error :lambdaEquality_alt, 
equalityTransitivity, 
equalitySymmetry, 
Error :inhabitedIsType, 
Error :dependent_set_memberEquality_alt, 
Error :isect_memberEquality_alt, 
Error :productIsType, 
instantiate, 
Error :setIsType, 
functionEquality, 
baseApply, 
closedConclusion, 
equalityElimination, 
promote_hyp, 
hypothesis_subsumption
Latex:
\mforall{}[T:Type].  \mforall{}[as:T  List].  \mforall{}[n:\{0...||as||\}].  \mforall{}[i:\mBbbN{}n].    (firstn(n;as)[i]  =  as[i])
Date html generated:
2019_06_20-PM-00_43_28
Last ObjectModification:
2018_10_08-PM-00_19_06
Theory : list_0
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