A Bilevel Hierarchy of Strengthened Complex Moment Relaxations for Complex Polynomial Optimization
Jie Wang
TL;DR
This work tackles slow convergence in complex polynomial optimization by introducing a bilevel strengthened complex moment hierarchy that leverages normality-inspired PSD constraints tied to a second-order parameter $s$. The approach yields a family of relaxations $tauPrime_{r,s}$ that tighten bounds without increasing the outer order and can be integrated with correlative sparsity for scalability. The authors establish a theoretical link between these constraints and the normality of shift operators, provide monotonicity and convergence insights under sphere constraints, and demonstrate substantial empirical gains across quadratic, quartic, and conjecture-related problems. Overall, the method delivers tighter bounds at lower computational cost, broadening the practical applicability of complex moment relaxations in areas like signal processing, power systems, quantum information, and combinatorial optimization.
Abstract
This paper proposes a bilevel hierarchy of strengthened complex moment relaxations for complex polynomial optimization. The key trick entails considering a class of positive semidefinite conditions that arise naturally in characterizing the normality of the so-called shift operators. The relaxation problem in this new hierarchy is parameterized by the usual relaxation order as well as an extra normal order, thus providing more space of flexibility to balance the strength of relaxation and computational complexity. Extensive numerical experiments demonstrate the superior performance of the new hierarchy compared to the usual hierarchy.
