@article{2001475, title={Non-Convex Relaxation to the Space of Hypercomplex Numbers for Indefinite Quadratic Programming-Properties and Optimization Algorithms}, author={Kohei MORI and Shinji HARA}, journal={Transactions of the Institute of Systems, Control and Information Engineers}, volume={14}, number={10}, pages={475-482}, year={2001}, doi={10.5687/iscie.14.475} }