3月2日消息，亚马逊云服务（AWS）公告确认，其位于中东阿联酋区域的一个核心数据中心在当地时间3月1日凌晨遭遇突发物理事故，导致该区域部分服务出现大面积中断或延迟。当日凌晨4:30左右，该区域内的一个可用区（mec1-az2）遭到外部物体撞击，撞击直接导致机房产生火花并引发火灾。为配合消防部门灭火，该设施的市政供电及备用发电机已全部被迫切断。目前消防工作仍在进行，AWS技术团队正等待进入现场进行电力恢复。AWS官方表示，即使在获得电力恢复许可后，重新建立网络连接和硬件自检仍需数小时的时间。目前的初步评估显示，完全恢复仍有较长路径。
Jake Kwon,Seoul correspondentand
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Sources said the government had set up a "huge operation" which had at times seemed "hostile and difficult" to the inquiry.
A Riemannian metric on a smooth manifold \(M\) is a family of inner products \[g_p : T_pM \times T_pM \;\longrightarrow\; \mathbb{R}, \qquad p \in M,\] varying smoothly in \(p\), such that each \(g_p\) is symmetric and positive-definite. In local coordinates the metric is completely determined by its values on basis tangent vectors: \[g_{ij}(p) \;:=\; g_p\!\left(\frac{\partial}{\partial x^i}\bigg|_p,\; \frac{\partial}{\partial x^j}\bigg|_p\right), \qquad g_{ij} = g_{ji},\] with the matrix \((g_{ij}(p))\) positive-definite at every point. The length of a tangent vector \(v = \sum_i v^i \frac{\partial}{\partial x^i}\in T_pM\) is then \(\|v\|_g = \sqrt{\sum_{i,j} g_{ij}(p)\, v^i v^j}\).
Type booleans are a special subset of the type language that can be