Nuprl Lemma : near-inverse-of-increasing-function-ext
∀f:ℝ ⟶ ℝ. ∀n,M:ℕ+. ∀z:ℝ. ∀a,b:ℤ.
  ∀k:ℕ+
    (∃c:ℤ. (∃j:ℕ+ [((|f[(r(c))/j] - z| ≤ (r1/r(n))) ∧ ((r(a))/k ≤ (r(c))/j) ∧ ((r(c))/j ≤ (r(b))/k))])) supposing 
       ((z ≤ f[(r(b))/k]) and 
       (f[(r(a))/k] ≤ z) and 
       (∀x,y:ℝ.
          (((r(a))/k ≤ x)
          
⇒ (x < y)
          
⇒ (y ≤ (r(b))/k)
          
⇒ ((f[x] ≤ f[y]) ∧ (((y - x) ≤ (r1/r(M))) 
⇒ ((f[y] - f[x]) ≤ (r1/r(n)))))))) 
  supposing a < b
Proof
Definitions occuring in Statement : 
rdiv: (x/y)
, 
rleq: x ≤ y
, 
rless: x < y
, 
rabs: |x|
, 
int-rdiv: (a)/k1
, 
rsub: x - y
, 
int-to-real: r(n)
, 
real: ℝ
, 
nat_plus: ℕ+
, 
less_than: a < b
, 
uimplies: b supposing a
, 
so_apply: x[s]
, 
all: ∀x:A. B[x]
, 
sq_exists: ∃x:A [B[x]]
, 
exists: ∃x:A. B[x]
, 
implies: P 
⇒ Q
, 
and: P ∧ Q
, 
function: x:A ⟶ B[x]
, 
natural_number: $n
, 
int: ℤ
Definitions unfolded in proof : 
member: t ∈ T
, 
subtract: n - m
, 
so_apply: x[s]
, 
genrec-ap: genrec-ap, 
near-inverse-of-increasing-function, 
decidable__le, 
uniform-comp-nat-induction, 
nearby-cases, 
decidable__and, 
decidable__not, 
decidable__less_than', 
decidable__lt, 
rleq_functionality_wrt_implies, 
decidable__implies, 
decidable__false, 
any: any x
, 
decidable__squash, 
decidable_functionality, 
squash_elim, 
sq_stable_from_decidable, 
iff_preserves_decidability, 
sq_stable__from_stable, 
stable__from_decidable, 
uall: ∀[x:A]. B[x]
, 
so_lambda: so_lambda(x,y,z,w.t[x; y; z; w])
, 
so_apply: x[s1;s2;s3;s4]
, 
so_lambda: λ2x.t[x]
, 
top: Top
, 
uimplies: b supposing a
Lemmas referenced : 
near-inverse-of-increasing-function, 
lifting-strict-decide, 
istype-void, 
strict4-decide, 
lifting-strict-less, 
lifting-strict-callbyvalue, 
decidable__le, 
uniform-comp-nat-induction, 
nearby-cases, 
decidable__and, 
decidable__not, 
decidable__less_than', 
decidable__lt, 
rleq_functionality_wrt_implies, 
decidable__implies, 
decidable__false, 
decidable__squash, 
decidable_functionality, 
squash_elim, 
sq_stable_from_decidable, 
iff_preserves_decidability, 
sq_stable__from_stable, 
stable__from_decidable
Rules used in proof : 
introduction, 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
cut, 
instantiate, 
extract_by_obid, 
hypothesis, 
sqequalRule, 
thin, 
sqequalHypSubstitution, 
equalityTransitivity, 
equalitySymmetry, 
isectElimination, 
baseClosed, 
isect_memberEquality_alt, 
voidElimination, 
independent_isectElimination
Latex:
\mforall{}f:\mBbbR{}  {}\mrightarrow{}  \mBbbR{}.  \mforall{}n,M:\mBbbN{}\msupplus{}.  \mforall{}z:\mBbbR{}.  \mforall{}a,b:\mBbbZ{}.
    \mforall{}k:\mBbbN{}\msupplus{}
        (\mexists{}c:\mBbbZ{}
            (\mexists{}j:\mBbbN{}\msupplus{}  [((|f[(r(c))/j]  -  z|  \mleq{}  (r1/r(n)))
                          \mwedge{}  ((r(a))/k  \mleq{}  (r(c))/j)
                          \mwedge{}  ((r(c))/j  \mleq{}  (r(b))/k))]))  supposing 
              ((z  \mleq{}  f[(r(b))/k])  and 
              (f[(r(a))/k]  \mleq{}  z)  and 
              (\mforall{}x,y:\mBbbR{}.
                    (((r(a))/k  \mleq{}  x)
                    {}\mRightarrow{}  (x  <  y)
                    {}\mRightarrow{}  (y  \mleq{}  (r(b))/k)
                    {}\mRightarrow{}  ((f[x]  \mleq{}  f[y])  \mwedge{}  (((y  -  x)  \mleq{}  (r1/r(M)))  {}\mRightarrow{}  ((f[y]  -  f[x])  \mleq{}  (r1/r(n)))))))) 
    supposing  a  <  b
Date html generated:
2019_10_29-AM-10_07_00
Last ObjectModification:
2019_02_05-PM-04_47_42
Theory : reals
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