Nonstrictly hyperbolic systems with stiff relaxation terms

In this paper, a zero factor idea is introduced to extend the convergence framework in [G.-Q. Chen, C.D. Levermore, T.-P. Liu, Hyperbolic conservation laws with stiff relaxation terms and entropy, Comm. Pure Appl. Math. 47 (1994) 787–830] for the singular limits of stiff relaxation from general 2×2 hyperbolic conservation systems to nonstrictly hyperbolic systems and an application of this framework on the so-called system of extended traffic flow is obtained.