论文标题
整数编程和发病率
Integer Programming and Incidence Treedepth
论文作者
论文摘要
最近,在一侧的整数编程(IP)的障碍性(IP)的障碍性之间显示了牢固的联系,另一侧的结构在另一侧的结构。为此,相对于其约束矩阵的Gaifman图和最大系数(绝对值)的Gaifman图,整数线性编程是可固定参数的固定参数。在此的激励下,Kotecký,Levin和Onn [ICALP 2018]询问是否可以将这些结果扩展到更广泛的整数线性程序。更正式的是,整数线性编程是否可以相对于其约束矩阵的发病率和最大系数(绝对值)的固定参数进行处理? 我们以负面的方式回答这个问题。特别是,我们证明了以标准形式确定系统的可行性,$ {a \ mathbf {x} = \ MathBf {b}},{\ Mathbf {l} \ le \ le \ le \ le \ mathbf {x} \ le \ le \ le \ le \ le \ \ mathbf {u}} $在$ a中,$是1,而发射率的$ a $为5。此外,我们通过显示自然的障碍和仅限制性设置的障碍,即:(1)在约束的最大值或变量出现的最大发生数量以及(2)顶点覆盖码上,对这种顽固性的补充。
Recently a strong connection has been shown between the tractability of integer programming (IP) with bounded coefficients on the one side and the structure of its constraint matrix on the other side. To that end, integer linear programming is fixed-parameter tractable with respect to the primal (or dual) treedepth of the Gaifman graph of its constraint matrix and the largest coefficient (in absolute value). Motivated by this, Koutecký, Levin, and Onn [ICALP 2018] asked whether it is possible to extend these result to a more broader class of integer linear programs. More formally, is integer linear programming fixed-parameter tractable with respect to the incidence treedepth of its constraint matrix and the largest coefficient (in absolute value)? We answer this question in negative. In particular, we prove that deciding the feasibility of a system in the standard form, ${A\mathbf{x} = \mathbf{b}}, {\mathbf{l} \le \mathbf{x} \le \mathbf{u}}$, is $\mathsf{NP}$-hard even when the absolute value of any coefficient in $A$ is 1 and the incidence treedepth of $A$ is 5. Consequently, it is not possible to decide feasibility in polynomial time even if both the assumed parameters are constant, unless $\mathsf{P}=\mathsf{NP}$. Moreover, we complement this intractability result by showing tractability for natural and only slightly more restrictive settings, namely: (1) treedepth with an additional bound on either the maximum arity of constraints or the maximum number of occurrences of variables and (2) the vertex cover number.