Shin Isojima and Hirotaka Toyama. Ultradiscrete analogues of the hard-spring equation and its conserved quantity. Japan J. Indust. Appl. Math. 2019. 36. 1. 53-78
Ultradiscretization with parity variables of the hard-spring equation and its conserved quantity
(China-Japan Joint Workshop on Integrable Systems 2019 2019)