Remark on Non-Uniform Fundamental and Non Smooth Solutions of Some Classes of Differential Operators with Double Characteristics
Nguyễn Minh Trí · Institutional Repositories DataBase (IRDB) · 1999
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).