Abstract
Estimating the number of isolated roots of a polynomial system is not only a fundamental study theme in algebraic geometry but also an important subproblem of homotopy methods for solving polynomial systems. For the mixed trigonometric polynomial systems, which are more general than polynomial systems and rather frequently occur in many applications, the classical Bézout number and the multihomogeneous Bézout number are the best known upper bounds on the number of isolated roots. However, for the deficient mixed trigonometric polynomial systems, these two upper bounds are far greater than the actual number of isolated roots. The BKK bound is known as the most accurate upper bound on the number of isolated roots of a polynomial system. However, the extension of the definition of the BKK bound allowing it to treat mixed trigonometric polynomial systems is very difficult due to the existence of sine and cosine functions. In this paper, two new upper bounds on the number of isolated roots of a mixed trigonometric polynomial system are defined and the corresponding efficient algorithms for calculating them are presented. Numerical tests are also given to show the accuracy of these two definitions, and numerically prove they can provide tighter upper bounds on the number of isolated roots of a mixed trigonometric polynomial system than the existing upper bounds, and also the authors compare the computational time for calculating these two upper bounds.
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This research was supported in part by the National Natural Science Foundation of China under Grant Nos. 11101067 and 11571061, Major Research Plan of the National Natural Science Foundation of China under Grant No. 91230103 and the Fundamental Research Funds for the Central Universities.
This paper was recommended for publication by Editor ZHANG Yang.
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Jiao, L., Dong, B. & Yu, B. Efficiently counting affine roots of mixed trigonometric polynomial systems. J Syst Sci Complex 30, 967–982 (2017). https://doi.org/10.1007/s11424-017-5214-9
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DOI: https://doi.org/10.1007/s11424-017-5214-9