The secret of Fermat's last theorem will be discussed at a lecture by Prof Yves Hellegouarch of the University of Caen in Theatre N, Arts Building, UCD Belfield, next Thursday at 7.30 p.m. Admission is free. The theorem defeated the best efforts of the sharpest minds for more than 350 years before being solved, the mathematical event of the century. Prof Hellegouarch was involved in work leading to the solution.