Symmetry is all around us, from the repeating patterns of crystals to the stitches in a knitted sweater. In materials science, these patterns are more than just visually appealing: They can influence how a material conducts heat, transports electricity and interacts with light. Now, an international research team led by Tohoku University's Advanced Institute for Materials Research (WPI-AIMR) has developed a mathematical framework for describing symmetry in complex, layered structures, opening new possibilities for understanding and designing functional materials. Their findings are published in the journal Interface Focus.