English

Solution of the truncated hyperbolic moment problem

Functional Analysis 2007-05-23 v1

Abstract

Let Q(x,y)=0 be an hyperbola in the plane. Given real numbers ββ2n)={βij}i,j0,i+j2n\beta \equiv\beta^{2n)}=\{\beta_{ij}\}_{i,j\geq0,i+j\leq2n}, with β00>0\beta_{00}>0, the truncated Q-hyperbolic moment problem for \beta entails finding necessary and sufficient conditions for the existence of a positive Borel measure \mu, supported in Q(x,y)=0, such that βij=yixjdμ(0i+j2n)\beta_{ij}=\int y^{i}x^{j} d\mu (0\leq i+j\leq2n). We prove that \beta admits a Q-representing measure \mu (as above) if and only if the associated moment matrix M(n)(β)\mathcal{M}(n)(\beta) is positive semidefinite, recursively generated, has a column relation Q(X,Y)=0, and the algebraic variety V(β)\mathcal{V}(\beta) associated to \beta satisfies cardV(β)\rankM(n)(β)card\mathcal{V}(\beta)\geq\rank\mathcal{M}(n)(\beta). In this case, rankM(n)2n+1rank\mathcal{M}(n)\leq2n+1; if rankM(n)2nrank\mathcal{M}(n)\leq2n, then \beta admits a rankM(n)rank\mathcal{M}(n)-atomic (minimal) Q-representing measure; if rankM(n)=2n+1rank\mathcal{M}(n)=2n+1, then \beta admits a Q-representing measure \mu satisfying 2n+1\leqcardsuppμ2n+22n+1\leqcard supp\mu\leq2n+2.

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Cite

@article{arxiv.math/0507069,
  title  = {Solution of the truncated hyperbolic moment problem},
  author = {Raul E. Curto and Lawrence A. Fialkow},
  journal= {arXiv preprint arXiv:math/0507069},
  year   = {2007}
}