TY - JOUR
T1 - Entropy Methods for Nonstrictly Hyperbolic Systems
AU - Marcati Pierangelo  & Rubino Bruno 
JO - Journal of Partial Differential Equations
VL - 4
SP - 333
EP - 346
PY - 1997
DA - 1997/10
SN - 10
DO - http://doi.org/
UR - https://global-sci.org/intro/article_detail/jpde/5603.html
KW - Conservation laws
KW - entropy
KW - Goursat problem
KW - nonlinear wave equation
KW - Riemann function
KW - sonic line
KW - weak and strong fundamental solutions
AB -  This paper regards the existence of entropy waves for a model example of nonstrictly hyperbolic system which degenerates on a sonic line. This construction is an important tool to approach the convergence of the vanishing viscosity and of other similar approximations to the weak solutions of the hyperbolic systems, via the compensated compactness techniques.