Eighteen-year-old Bulgarian student Nikola Veselinov won the $75,000 Regeneron Young Scientist Award at the 2026 Regeneron International Science and Engineering Fair (ISEF) for developing a new mathematical theorem. His research explains when certain equations cannot be solved using elementary mathematical functions by combining topology, symmetry and Galois theory. The achievement highlights the importance of pure mathematics in advancing scientific understanding and demonstrates how young researchers can contribute to solving longstanding theoretical challenges.