论文标题
用于预算的Matroid独立集的EPTA
An EPTAS for Budgeted Matroid Independent Set
论文作者
论文摘要
我们考虑预算的Matroid独立集问题。该输入是一个地面集,每个要素都有成本和非负利润,以及在元素和预算上的矩阵。目的是选择一个元素的子集,以最大程度地利用矩阵和预算约束。几个众所周知的特殊情况,例如,我们有一个均匀的矩阵和预算,或没有矩阵约束(即经典的背包问题),该案例接受了完全多项式时近似方案(FPTAS)。相比之下,已经对多预算的矩阵独立集问题进行了略微概括,但不接受有效的多项式时间近似方案(EPTAS)。这意味着我们问题的PTA,这是这项工作之前最著名的结果。我们的主要贡献是针对预算的Matroid独立集问题的EPTA。该方案的一个关键思想是为实例找到代表性集,其基数仅取决于$ 1/\ varepsilon $,其中$ \ varepsilon> 0 $是该方案的准确性参数。代表性集是通过矩阵基础最小化确定的,可以通过简单的贪婪算法来求解。我们的方案对代表集的子集进行了列举,并使用线性程序扩展了每个子集。代表性集的概念可能有助于解决预算的Matroid独立集问题的其他变体。
We consider the budgeted matroid independent set problem. The input is a ground set, where each element has a cost and a non-negative profit, along with a matroid over the elements and a budget. The goal is to select a subset of elements which maximizes the total profit subject to the matroid and budget constraints. Several well known special cases, where we have, e.g., a uniform matroid and a budget, or no matroid constraint (i.e., the classic knapsack problem), admit a fully polynomial-time approximation scheme (FPTAS). In contrast, already a slight generalization to the multi-budgeted matroid independent set problem has a PTAS but does not admit an efficient polynomial-time approximation scheme (EPTAS). This implies a PTAS for our problem, which is the best known result prior to this work. Our main contribution is an EPTAS for the budgeted matroid independent set problem. A key idea of the scheme is to find a representative set for the instance, whose cardinality depends solely on $1/\varepsilon$, where $\varepsilon > 0$ is the accuracy parameter of the scheme. The representative set is identified via matroid basis minimization, which can be solved by a simple greedy algorithm. Our scheme enumerates over subsets of the representative set and extends each subset using a linear program. The notion of representative sets may be useful in solving other variants of the budgeted matroid independent set problem.