2 problems

Let $u$ be the solution of the homogeneous reaction-diffusion equation with initial datum as in the paper, let $X_\lambda(t,x')$ be its $\lambda$-level set, and let $\varphi$ be th…

Let $A$ be the set of points $(c,n)$ such that $c$ is a nontrivial coefficient of $\Phi_n$, and let $A_k$ consist of those points in $A$ with $n\leq k$. For each $k$, write…