#### HDBSCAN

• 核心距离$core_k(x)$：

• 互达距离：mutual reachability distance

#### 最小生成子树

The right thing to do is to find a minimal set of edges such that dropping any edge from the set causes a disconnection of components. But we need more, we need this set to be such that there is no lower weight edge that could connect the components. Fortunately graph theory furnishes us with just such a thing: the minimum spanning tree of the graph.

MST性质：

#### 提取团簇

• 当前团簇分裂为两个子团簇
• 当前团簇分裂为一个大的团簇和几个离散点。

$\lambda_{\mathrm{birth}}$：团簇形成时的 $\lambda$ 值
$\lambda_{\mathrm{death}}$：团簇分裂为两个子团簇时的 $\lambda$ 值
$\lambda_p$：点 $p$ 从团簇中分离出去时的 $\lambda$ 值