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Solution of the Truncated Hyperbolic Moment Problem
Journal article   Peer reviewed

Solution of the Truncated Hyperbolic Moment Problem

Raúl Curto and Lawrence Fialkow
Integral Equations and Operator Theory, Vol.52(2), pp.181-218
06/2005
DOI: 10.1007/s00020-004-1340-6

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Abstract

Let Q(x, y) = 0 be an hyperbola in the plane. Given real numbers β ≡ β (2n)={ β ij } i,j ≥ 0,i+j ≤ 2n , with β00 > 0, the truncated Q-hyperbolic moment problem for β entails finding necessary and sufficient conditions for the existence of a positive Borel measure μ, supported in Q(x, y) = 0, such that $$\beta _{ij} = \int {y^i x^j d\mu } \quad (0 \leq i + j \leq 2n).$$ We prove that β admits a Q-representing measure μ (as above) if and only if the associated moment matrix $$\mathcal{M}(n)(\beta )$$ is positive semidefinite, recursively generated, has a column relation Q(X,Y) = 0, and the algebraic variety $$\mathcal{V}(\beta )$$ associated to β satisfies card $$\mathcal{V}(\beta ) \geq {\text{rank }}\mathcal{M}(n)(\beta ).$$ In this case, $${\text{rank }}\mathcal{M}(n) \leq 2n + 1;$$ if $${\text{rank }}\mathcal{M}(n) \leq 2n,$$ then β admits a rank $$\mathcal{M}(n)$$ -atomic (minimal) Q-representing measure; if $${\text{rank }}\mathcal{M}(n) = 2n + 1,$$ then β admits a Q-representing measure μ satisfying $$2n + 1 \leq {\text{card supp }}\mu \leq 2n + 2.$$
Secondary 15A57 15-04 42A70 Mathematics 47A20 30A05 44A60 flat extensions of positive matrices 47N40 moment matrix extension Hyperbolic moment problem Analysis Primary 47A57

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