|GARY WALSH, Department of Mathematics, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada|
|Old and new results on quartic diophantine equations|
During his illustrious career, Wilhelm Ljunggren proved many results on the solvability of Diophantine equations of the form aX4-bY2=c. In this talk we present some of Ljunggren's work, some problems remaining from his work, and recent progress on these outstanding problems. This is joint work with M. A. Bennett.