Moment Problem
Please inform me if you have an
idea in the question stated below.
@We cite a paper :
Codimension
of polynomial subspace in
@for discrete indeterminate measure
.
Andrew G.Bakan,
Proceedings of the AMS,(2002)vol.130,no 12,3545-3553
Abstracts:
Let
be the set of positive Borel
measures on the real line
@with moments of all
orders. A measure
is said to be indeterminate if the set
@contains at least one
measure
other than@
@@@where
@is a set of measures
such that
@![]()
Theorem 1.Let
![]()
be any discrete indeterminate measure from the class
.
Then the following statements hold.
(A)If
,

where codim
@denotes the codimension of the closures of the algebraic polynomials
in
.
(B)If
@is an n-canonical
measure for some nonnegative integer n, then@ there exist numbers
,
such that
,
, ![]()
I am here interested in a
relation between the part (B) in this Theorem and the Cassiefs Proposition in
the following.
Cassier has characterized
n canonical measures in the following way:
Proposition 4. Soit
@une
measure ayant des moments de tous
les orders,
@un entire,
@des points distincts de
@nfapartement
pas au support de
, et
@des constantes strictement positives.
On a alors les equivalences:
a)
@est N-extremale;
b)
.
Measures Canoniques dan le Problem Classique des Momens.
Ann.Inst.Fourier,
Question[1]:
Is Cassierfs
Proposition@ a special case of the Bakanfs Theorem 1 ?
For example
@for n points of k. Doesfnt this be permitted?
Question[2]:
is known to be a value at
of some N-extremal measure.
Cassierfs@ proposition@
said that n-canonocal measures are larger than
N-extremal measure for n supporting points. But Theorem
1 seems to describe that n canonical measure is less than N-extremal
measure@
@in
.
Is this a contradiction?@ I think that itfs not, and@ that
fs@ should come from more
than two N-extremal measures. Probably they come from
the n N-extremal measures.
Akio Arimoto
Musashi Institute of
Technology,
Setagaya-ku@Tamazutumi@P|QX|P,158
Barry Simon The classical moment
problem as a self-adjoint finite difference operator
1997,Advances
in Mathematics, arXiv:math-ph/9906008
Theorem 4.17, (p.45)
![]()
where
. These are rewritten by Bakan as
the following way:
![]()
.
We have
,
@is the rational
function of the order n.
Hence 
2002/10/25
Bakan wrote
,
whose denominator and
nominator are by Nevalinna
@(1)
.(2)
Real numbers
fs are zeros of
,
,
(3)
in
the same time they are support points of
.
It is easy that
.
Now let
@be zeros of the polynomial
,
, ![]()
From (1),(2) and (3),

and hence we have
![]()
von Neumann
extremal measure
@is obtained by making
.
Thus we have
.
Hence
![]()
![]()
![]()
![]()
. In other words,
, and
.
By Lagrange interpolation formula, we have
,
and by differentiating both sides, we have

.
Putting
,
![]()