Nuprl Lemma : cantor-interval-length
∀[a,b:ℝ]. ∀[n:ℕ]. ∀[f:ℕn ⟶ 𝔹].  (((snd(cantor-interval(a;b;f;n))) - fst(cantor-interval(a;b;f;n))) = (2^n * b - a)/3^n)
Proof
Definitions occuring in Statement : 
cantor-interval: cantor-interval(a;b;f;n)
, 
int-rdiv: (a)/k1
, 
int-rmul: k1 * a
, 
rsub: x - y
, 
req: x = y
, 
real: ℝ
, 
exp: i^n
, 
int_seg: {i..j-}
, 
nat: ℕ
, 
bool: 𝔹
, 
uall: ∀[x:A]. B[x]
, 
pi1: fst(t)
, 
pi2: snd(t)
, 
function: x:A ⟶ B[x]
, 
natural_number: $n
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x]
, 
member: t ∈ T
, 
nat: ℕ
, 
implies: P 
⇒ Q
, 
false: False
, 
ge: i ≥ j 
, 
uimplies: b supposing a
, 
not: ¬A
, 
satisfiable_int_formula: satisfiable_int_formula(fmla)
, 
exists: ∃x:A. B[x]
, 
all: ∀x:A. B[x]
, 
top: Top
, 
and: P ∧ Q
, 
prop: ℙ
, 
cantor-interval: cantor-interval(a;b;f;n)
, 
decidable: Dec(P)
, 
or: P ∨ Q
, 
pi2: snd(t)
, 
pi1: fst(t)
, 
int_nzero: ℤ-o
, 
nequal: a ≠ b ∈ T 
, 
int_seg: {i..j-}
, 
lelt: i ≤ j < k
, 
subtype_rel: A ⊆r B
, 
le: A ≤ B
, 
less_than': less_than'(a;b)
, 
iff: P 
⇐⇒ Q
, 
rev_implies: P 
⇐ Q
, 
uiff: uiff(P;Q)
, 
subtract: n - m
, 
true: True
, 
sq_stable: SqStable(P)
, 
squash: ↓T
, 
nat_plus: ℕ+
, 
less_than: a < b
, 
rneq: x ≠ y
, 
guard: {T}
, 
rless: x < y
, 
sq_exists: ∃x:A [B[x]]
, 
so_lambda: λ2x.t[x]
, 
so_apply: x[s]
, 
rev_uimplies: rev_uimplies(P;Q)
, 
sq_type: SQType(T)
, 
lt_int: i <z j
, 
ifthenelse: if b then t else f fi 
, 
btrue: tt
, 
bool: 𝔹
, 
unit: Unit
, 
it: ⋅
, 
bfalse: ff
, 
bnot: ¬bb
, 
assert: ↑b
, 
rdiv: (x/y)
, 
req_int_terms: t1 ≡ t2
Lemmas referenced : 
nat_properties, 
full-omega-unsat, 
intformand_wf, 
intformle_wf, 
itermConstant_wf, 
itermVar_wf, 
intformless_wf, 
istype-int, 
int_formula_prop_and_lemma, 
istype-void, 
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, 
req_witness, 
rsub_wf, 
cantor-interval_wf, 
decidable__le, 
intformnot_wf, 
int_formula_prop_not_lemma, 
istype-le, 
int-rdiv_wf, 
exp_wf3, 
intformeq_wf, 
int_formula_prop_eq_lemma, 
nequal_wf, 
int-rmul_wf, 
exp_wf2, 
subtract-1-ge-0, 
istype-nat, 
real_wf, 
int_seg_wf, 
int_seg_properties, 
req_weakening, 
subtype_rel_function, 
bool_wf, 
subtract_wf, 
int_seg_subtype, 
istype-false, 
not-le-2, 
condition-implies-le, 
add-associates, 
minus-add, 
minus-one-mul, 
add-swap, 
minus-one-mul-top, 
add-mul-special, 
zero-mul, 
add-zero, 
add-commutes, 
le-add-cancel2, 
subtype_rel_self, 
sq_stable__req, 
ifthenelse_wf, 
lt_int_wf, 
itermSubtract_wf, 
int_term_value_subtract_lemma, 
decidable__lt, 
radd_wf, 
exp_step, 
exp-positive-stronger, 
rless-int, 
nat_plus_properties, 
rmul_preserves_req, 
rless_wf, 
int-to-real_wf, 
req_wf, 
rdiv_wf, 
rmul_wf, 
rminus_wf, 
itermMultiply_wf, 
itermAdd_wf, 
itermMinus_wf, 
rinv_wf2, 
int_term_value_mul_lemma, 
rneq_functionality, 
rmul-int, 
rneq-int, 
set_subtype_base, 
less_than_wf, 
int_subtype_base, 
subtype_base_sq, 
decidable__equal_int, 
req-iff-rsub-is-0, 
nat_plus_inc_int_nzero, 
primrec-unroll, 
exp0_lemma, 
req_functionality, 
req_transitivity, 
int-rdiv-one, 
int-rmul-one, 
eqtt_to_assert, 
assert_of_lt_int, 
eqff_to_assert, 
bool_cases_sqequal, 
bool_subtype_base, 
assert-bnot, 
iff_weakening_uiff, 
assert_wf, 
int-rdiv-req, 
rsub_functionality, 
rdiv_functionality, 
int-rmul-req, 
radd_functionality, 
rmul_functionality, 
rmul-rinv3, 
real_polynomial_null, 
real_term_value_sub_lemma, 
real_term_value_mul_lemma, 
real_term_value_var_lemma, 
real_term_value_add_lemma, 
real_term_value_minus_lemma, 
real_term_value_const_lemma, 
req_inversion, 
rminus_functionality, 
rinv-mul-as-rdiv, 
rinv-of-rmul, 
int-rinv-cancel
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation_alt, 
introduction, 
cut, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
thin, 
hypothesisEquality, 
hypothesis, 
setElimination, 
rename, 
intWeakElimination, 
lambdaFormation_alt, 
natural_numberEquality, 
independent_isectElimination, 
approximateComputation, 
independent_functionElimination, 
dependent_pairFormation_alt, 
lambdaEquality_alt, 
int_eqEquality, 
dependent_functionElimination, 
isect_memberEquality_alt, 
voidElimination, 
sqequalRule, 
independent_pairFormation, 
universeIsType, 
isectIsTypeImplies, 
inhabitedIsType, 
functionIsTypeImplies, 
dependent_set_memberEquality_alt, 
unionElimination, 
productElimination, 
equalityIstype, 
equalityTransitivity, 
equalitySymmetry, 
because_Cache, 
baseClosed, 
sqequalBase, 
intEquality, 
functionIsType, 
applyEquality, 
addEquality, 
minusEquality, 
multiplyEquality, 
productEquality, 
independent_pairEquality, 
productIsType, 
imageMemberEquality, 
imageElimination, 
inrFormation_alt, 
closedConclusion, 
baseApply, 
instantiate, 
cumulativity, 
equalityElimination, 
promote_hyp
Latex:
\mforall{}[a,b:\mBbbR{}].  \mforall{}[n:\mBbbN{}].  \mforall{}[f:\mBbbN{}n  {}\mrightarrow{}  \mBbbB{}].
    (((snd(cantor-interval(a;b;f;n)))  -  fst(cantor-interval(a;b;f;n)))  =  (2\^{}n  *  b  -  a)/3\^{}n)
Date html generated:
2019_10_30-AM-07_37_38
Last ObjectModification:
2018_12_16-PM-04_42_33
Theory : reals
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