Evans Pde Solutions Chapter 4 Here
The envelope of these planes for varying $\theta$ gives $u = \sqrtx^2 + y^2$ (the cone). This is the singular solution.
One of the most famous topics in this chapter is the . It provides a way to transform the nonlinear viscous Burgers' equation into the linear heat equation. Other methods include: evans pde solutions chapter 4
The fifth exercise in Chapter 4 concerns the traces of Sobolev functions. We need to show that if $u \in W^1,p(\Omega)$, then the trace of $u$ on the boundary $\partial \Omega$ is well-defined. The envelope of these planes for varying $\theta$