Charney's CAT(0) conjecture for Artin groups

Let an Artin group be the group associated to a symmetric matrix $(m_{ij})$ with entries in $\{2,3,\dots\}\cup\{\infty\}$, generated by $s_1,\ldots,s_n$ subject to the braid relations

$$\underbrace{s_is_js_i\cdots}_{m_{ij}\text{ factors}}=\underbrace{s_js_is_j\cdots}_{m_{ij}\text{ factors}}.$$

Here $m_{ij}=\infty$ means that there is no defining relation between $s_i$ and $s_j$. Charney's conjecture. Every Artin group is $\operatorname{CAT}(0)$, meaning that it acts properly and cocompactly on a $\operatorname{CAT}(0)$ space. The conjecture has been verified for right-angled Artin groups, namely Artin groups for which every $m_{ij}$ equals $2$ or $\infty$; the general assertion is therefore no longer open only in that special case.