Solution
= Solution
The <De Giorgi-Nash-Moser theorem> gives numbers $\alpha=\alpha(n,\lambda,\Lambda)\in(0,1)$ and $C=C(n,\lambda,\Lambda,\theta)$ such that every weak solution satisfies
$$
\boxed{\|u\|_{C^{0,\alpha}(B_\theta)}
\leq C\|u\|_{L^2(B_1)}}
$$
for each fixed $0<\theta<1$. In particular, every such weak solution has a locally Hölder-continuous representative despite the coefficients being only bounded and measurable.