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arXiv 1407.2679math.OC
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用于SOS分解的较小的SDP

Smaller SDP for SOS Decomposition

Liyun Dai, Bican Xia

摘要:

计算多项式平方和分解的一种流行的数值方法是将问题转化为半定规划问题,然后用半定规划求解器求解。在本文中,我们专注于减少SDP求解器的输入的大小,以提高这些SDP为基础的方法的效率和可靠性。定义了两种类型的多项式:凸覆盖多项式和分裂多项式。凸覆盖多项式或分裂多项式可以被分解成几个更小的子多项式,使得原始多项式是SOS当且仅当子多项式都是SOS。因此,原始SOS问题可以等效地分解成更小的子问题。证明了凸覆盖多项式是分裂多项式,多元稀疏多项式也很可能是分裂多项式,并在实际应用中可以有效地检测到。给出了多项式为SOS的若干必要条件,这些条件可以快速地反驳那些没有SOS表示的多项式,从而避免调用SDP求解器。所有新的结果导致一个新的SDP为基础的方法来计算SOS分解,这改善了这类方法通过较小的输入,SDP求解器在某些情况下。实验结果表明,该程序得到的单项式个数往往比其他SDP软件得到的单项式个数小于,特别是对于多变量高次多项式。各种测试的数值结果显示我们的程序的性能。

英文摘要:

A popular numerical method to compute SOS (sum of squares of polynomials) decompositions for polynomials is to transform the problem into semi-definite programming (SDP) problems and then solve them by SDP solvers. In this paper, we focus on reducing the sizes of inputs to SDP solvers to improve the efficiency and reliability of those SDP based methods. Two types of polynomials, convex cover polynomials and split polynomials, are defined. A convex cover polynomial or a split polynomial can be decomposed into several smaller sub-polynomials such that the original polynomial is SOS if and only if the sub-polynomials are all SOS. Thus the original SOS problem can be decomposed equivalently into smaller sub-problems. It is proved that convex cover polynomials are split polynomials and it is quite possible that sparse polynomials with many variables are split polynomials, which can be efficiently detected in practice. Some necessary conditions for polynomials to be SOS are also given, which can help refute quickly those polynomials which have no SOS representations so that SDP solvers are not called in this case. All the new results lead to a new SDP based method to compute SOS decompositions, which improves this kind of methods by passing smaller inputs to SDP solvers in some cases. Experiments show that the number of monomials obtained by our program is often smaller than that by other SDP based software, especially for polynomials with many variables and high degrees. Numerical results on various tests are reported to show the performance of our program.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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