Fig. 1 (image) Science China Press Share Print E-Mail Caption The definition of χ in systems with S4 symmetry on the orange surface S. The system in (b) has C2,110 symmetry. Credit @Science China Press Usage Restrictions Use with credits Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.