Hyperbolic Second Order Equations with Non-Regular Time Dependent Coefficients
Hyperbolic Second Order Equations with Non-Regular Time Dependent Coefficients
In this paper we study weakly hyperbolic second order equations with time dependent irregular coefficients. This means to assume that the coefficients are less regular than H\"older. The characteristic roots are also allowed to have multiplicities. For such equations, we describe the notion of a `very weak solution' adapted to …