On Activation Functions for Complex-Valued Neural Networks - Existence of Energy Functions. - Yasuaki Kuroe; Mitsuo Yoshida 002; Takehiro Mori (ICANN, 2003)

A Model of Hopfield-Type Quaternion Neural Networks and Its Energy Function. - Mitsuo Yoshida 002; Yasuaki Kuroe; Takehiro Mori (ICONIP, 2004)

Models of hopfield-type quaternion neural networks and their energy functions. - Mitsuo Yoshida 002; Yasuaki Kuroe; Takehiro Mori (Int. J. Neural Syst., 2005)