K_4 Crystal (IMAGE) American Mathematical Society Caption K_4 crystal. Created by Hisashi Naito. Credit Hisashi Naito Usage Restrictions Obtain permission from Professor Toshikazu Sunada, sunada@math.meiji.ac.jp License Licensed content 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.