论文标题
关于MaxSat变体的并行参数化复杂性
On the Parallel Parameterized Complexity of MaxSAT Variants
论文作者
论文摘要
在最大的满意度问题(最大 - SAT)中,我们将以结合形式的命题公式为命题公式,必须找到满足尽可能多的条款的分配。我们研究了各种版本的Max-SAT的并行参数化复杂性,并提供了第一个由解决方案大小或相对于某些保证的允许多余的恒定时间算法(“上述保证”版本)。对于双参数化版本,该参数是我们允许留下不满意的子句的数量,我们介绍了Max-2sat(称为近-2SAT)的第一个并行算法。在并行解决近2sat的困难源于以下事实:最初开发的迭代压缩方法完全可以证明该问题是固定参数可以拖延的,这是固有的顺序。我们观察到,可以并行计算该值为参数的图流程,并使用此事实为顶点覆盖问题开发一个并行算法,该算法在给定匹配的大小上方的参数上。最后,我们研究了通过顶点封面编号,TreeDepth,反馈顶点集号码和输入入射率图的树宽的最大值参数的平行复杂性。尽管Max-Sat是所有这些参数的固定参数,但我们表明它们允许不同程度的并行化程度。对于所有四种,我们开发了具有建设性的专用并行算法,这意味着它们输出了最佳分配 - 与可以通过并行元理论获得的结果相比,这通常只能解决决策版本。
In the maximum satisfiability problem (MAX-SAT) we are given a propositional formula in conjunctive normal form and have to find an assignment that satisfies as many clauses as possible. We study the parallel parameterized complexity of various versions of MAX-SAT and provide the first constant-time algorithms parameterized either by the solution size or by the allowed excess relative to some guarantee ("above guarantee" versions). For the dual parameterized version where the parameter is the number of clauses we are allowed to leave unsatisfied, we present the first parallel algorithm for MAX-2SAT (known as ALMOST-2SAT). The difficulty in solving ALMOST-2SAT in parallel comes from the fact that the iterative compression method, originally developed to prove that the problem is fixed-parameter tractable at all, is inherently sequential. We observe that a graph flow whose value is a parameter can be computed in parallel and use this fact to develop a parallel algorithm for the vertex cover problem parameterized above the size of a given matching. Finally, we study the parallel complexity of MAX-SAT parameterized by the vertex cover number, the treedepth, the feedback vertex set number, and the treewidth of the input's incidence graph. While MAX-SAT is fixed-parameter tractable for all of these parameters, we show that they allow different degrees of possible parallelization. For all four we develop dedicated parallel algorithms that are constructive, meaning that they output an optimal assignment - in contrast to results that can be obtained by parallel meta-theorems, which often only solve the decision version.