Sharp estimate of the life span of solutions to the heat equation with a nonlinear boundary condition

Kotaro Hisa

Consider the heat equation with a nonlinear boundary condition $$ \partial_t u=Δu,\quad x\in{\bf R}^N_+,\,\,\,t>0,\qquad \partial_νu=u^p, \quad x\in\partial{\bf R}^N_+,\,\,\,t>0,\q…