Graduate School of Mathematical Sciences, The University of Tokyo
Journal of Mathematical Sciences, The University of Tokyo. Vol. 6 (1999), No. 3, Page 437-452
We construct explicit formulas for fundamental solutions and non-smooth solutions at degenerate points of a model of Grushin's type operator. The results give all the discrete values of parameters where the operator is not hypoelliptic (nor analytic hypoelliptic).