Vg. Danilov et al., ALGEBRAS OF THE SINGULARITIES OF SINGULAR SOLUTIONS TO FIRST-ORDER QUASI-LINEAR STRICTLY HYPERBOLIC SYSTEMS, Theoretical and mathematical physics, 114(1), 1998, pp. 1-42
An associative commutative algebra of distributions that contains homo
geneous and associated homogeneous distributions is constructed. This
algebra is used to analyze generalized solutions to strictly hyperboli
c partial differential equations. Possible types of singularities are
studied and the necessary (analogues of Hugoniot conditions for shock
waves) and sufficient conditions for the existence of such solutions a
re obtained.