Huixu Deng, left, and Tiancheng Wang, of Missouri University of Science and Technology, work out the bugs in the software they wrote to drive the Cognitive and Autonomous Test, or CAT, vehicle near Old Main on the University of Arizona campus Tuesday April 25, 2017. U.S. and international students were in Tucson for the 2017 CAT Vehicle Challenge, sponsored by the National Science Foundation and MathWorks.