Cauchy Problem for Differential Operators with Double Characteristics : Non-Effectively Hyperbolic Characteristics

Features thorough discussions on well/ill-posedness of the Cauchy problem for differential operators with double characteristics of non-effectively hyperbolic type

Takes a unified approach combining geometrical and microlocal tools

Adopts the viewpoint that the Hamilton map and the geometry of bicharacteristics characterizes the well/ill-posedness of the Cauchy problem