“…For an elliptic and parabolic operator A, thanks to the maximum principle, we have the results of the time-global existence [12,19,23,25] for sufficiently small λ > 0, the quenching [12,18,23,25] for sufficiently large λ > 0, the connecting orbit [23], the Morse-Smale property [23], the location of the quenching point [17] and its stationary solution [5,6,7,11,13,23]. Also in the hyperbolic problem, we have similar results to those in the parabolic case, i.e., the global existence [3,26,38], the quenching [3,26,32,38], the estimate of the quenching time [32] and the singularity of the derivative [2]. In the damped hyperbolic case, we have the global existence [27] and quenching [15,27].…”