Topology (IMAGE) ETH Zurich Caption A doughnut can be turned into a coffee cup by pulling, stretching and molding. Topologically speaking, therefore, doughnuts and coffee cups are identical. Credit Sebastian Huber / ETH Zurich Usage Restrictions None 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.