4 problems

Linear conjecture. Nonlinear differential equations governing population spread always have the same propagation velocity as their linear approximation.

Let $b_1$ and $b_2$ be birth rates satisfying the assumptions of the paper, and let $s(b)$ denote the corresponding speed of propagation. Superadditivity conjecture. One has … This…

Consider the discrete-space process on $\mathbb{Z}^{\mathbb{Z}_+}$ with birth rate … where $a_{\mathrm{pow}}(x)=c_{\mathrm{pow}}/(|x|+1)^\alpha$ for $x\ne0$,…

Let $s(k)$ be the speed of propagation of the one-dimensional process with truncated birth rate, and let $b_\infty$ be the birth rate … Write $s_*$ for the speed of propagation of…