2 problems

Let $\sigma>0$ be the barrier speed in the isotropic fire problem, and let $\bar\sigma=2.6144\ldots$ denote the critical value obtained from the spectral analysis of the retarded d…

Let the fire propagate with unit speed in all directions from $R_0=B_1(0)$, and let the barrier be constructed at constant speed $\sigma>0$, so that $F=\overline{B_1(0)}$ and…