An induced subgraph is called an induced matching if each vertex is a degree-1 vertex in the subgraph. The \textsc{Almost Induced Matching} problem asks whether we can delete at most $k$ vertices from the input graph such that the remaining graph is an induced matching. This paper studies parameterized algorithms for this problem by taking the size $k$ of the deletion set as the parameter. First, we prove a $6k$-vertex kernel for this problem, improving the previous result of $7k$. Second, we give an $O^*(1.6765^k)$-time and polynomial-space algorithm, improving the previous running-time bound of $O^*(1.7485^k)$.
翻译:若一个导出子图中每个顶点都是度为1的顶点,则该子图称为诱导匹配。\textsc{几乎诱导匹配}问题询问是否可以从输入图中删除至多$k$个顶点,使得剩余图成为诱导匹配。本文以删除集大小$k$为参数,研究该问题的参数化算法。首先,我们证明该问题存在一个$6k$顶点的核,改进了此前$7k$的结果。其次,我们给出一个时间复杂度为$O^*(1.6765^k)$且空间复杂度为多项式的算法,改进了此前$O^*(1.7485^k)$的运行时间上界。