  Below are the problems that I formulated at Open Problems Session of {\it
Workshop on Group Actions on Rational Varieties}, McGill University and
University of Montreal, Canada, March 2002. To appear in: "Affine Algebraic
Geometry" conference Proceedings volume in Contemporary Mathematics series of
the Amer. Math. Soc. Ed. by Jaime Gutierrez, Vladimir Shpilrain, and Jie-Tai
Yu.
