{"title":"FPT algorithms for a special block-structured integer program with applications in scheduling","authors":"","doi":"10.1007/s10107-023-02046-z","DOIUrl":null,"url":null,"abstract":"<h3>Abstract</h3> <p>In this paper, a special case of the generalized 4-block <em>n</em>-fold IPs is investigated, where <span> <span>\\(B_i=B\\)</span> </span> and <em>B</em> has a rank at most 1. Such IPs, called <em>almost combinatorial 4-block n-fold IPs</em>, include the generalized <em>n</em>-fold IPs as a subcase. We are interested in fixed parameter tractable (FPT) algorithms by taking as parameters the dimensions of the blocks and the largest coefficient. For almost combinatorial 4-block <em>n</em>-fold IPs, we first show that there exists some <span> <span>\\(\\lambda \\le g(\\gamma )\\)</span> </span> such that for any nonzero kernel element <span> <span>\\({\\textbf{g}}\\)</span> </span>, <span> <span>\\(\\lambda {\\textbf{g}}\\)</span> </span> can always be decomposed into kernel elements in the same orthant whose <span> <span>\\(\\ell _{\\infty }\\)</span> </span>-norm is bounded by <span> <span>\\(g(\\gamma )\\)</span> </span> (while <span> <span>\\({\\textbf{g}}\\)</span> </span> itself might not admit such a decomposition), where <em>g</em> is a computable function and <span> <span>\\(\\gamma \\)</span> </span> is an upper bound on the dimensions of the blocks and the largest coefficient. Based on this, we are able to bound the <span> <span>\\(\\ell _{\\infty }\\)</span> </span>-norm of Graver basis elements by <span> <span>\\({\\mathcal {O}}(g(\\gamma )n)\\)</span> </span> and develop an <span> <span>\\({\\mathcal {O}}(g(\\gamma )n^{3+o(1)}\\hat{L}^2)\\)</span> </span>-time algorithm (here <span> <span>\\(\\hat{L}\\)</span> </span> denotes the logarithm of the largest absolute value occurring in the input). Additionally, we show that the <span> <span>\\(\\ell _{\\infty }\\)</span> </span>-norm of Graver basis elements is <span> <span>\\(\\varOmega (n)\\)</span> </span>. As applications, almost combinatorial 4-block <em>n</em>-fold IPs can be used to model generalizations of classical problems, including scheduling with rejection, bi-criteria scheduling, and a generalized delivery problem. Therefore, our FPT algorithm establishes a general framework to settle these problems.</p>","PeriodicalId":18297,"journal":{"name":"Mathematical Programming","volume":"34 1","pages":""},"PeriodicalIF":2.2000,"publicationDate":"2024-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Mathematical Programming","FirstCategoryId":"100","ListUrlMain":"https://doi.org/10.1007/s10107-023-02046-z","RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"COMPUTER SCIENCE, SOFTWARE ENGINEERING","Score":null,"Total":0}
引用次数: 0
Abstract
In this paper, a special case of the generalized 4-block n-fold IPs is investigated, where \(B_i=B\) and B has a rank at most 1. Such IPs, called almost combinatorial 4-block n-fold IPs, include the generalized n-fold IPs as a subcase. We are interested in fixed parameter tractable (FPT) algorithms by taking as parameters the dimensions of the blocks and the largest coefficient. For almost combinatorial 4-block n-fold IPs, we first show that there exists some \(\lambda \le g(\gamma )\) such that for any nonzero kernel element \({\textbf{g}}\), \(\lambda {\textbf{g}}\) can always be decomposed into kernel elements in the same orthant whose \(\ell _{\infty }\)-norm is bounded by \(g(\gamma )\) (while \({\textbf{g}}\) itself might not admit such a decomposition), where g is a computable function and \(\gamma \) is an upper bound on the dimensions of the blocks and the largest coefficient. Based on this, we are able to bound the \(\ell _{\infty }\)-norm of Graver basis elements by \({\mathcal {O}}(g(\gamma )n)\) and develop an \({\mathcal {O}}(g(\gamma )n^{3+o(1)}\hat{L}^2)\)-time algorithm (here \(\hat{L}\) denotes the logarithm of the largest absolute value occurring in the input). Additionally, we show that the \(\ell _{\infty }\)-norm of Graver basis elements is \(\varOmega (n)\). As applications, almost combinatorial 4-block n-fold IPs can be used to model generalizations of classical problems, including scheduling with rejection, bi-criteria scheduling, and a generalized delivery problem. Therefore, our FPT algorithm establishes a general framework to settle these problems.
期刊介绍:
Mathematical Programming publishes original articles dealing with every aspect of mathematical optimization; that is, everything of direct or indirect use concerning the problem of optimizing a function of many variables, often subject to a set of constraints. This involves theoretical and computational issues as well as application studies. Included, along with the standard topics of linear, nonlinear, integer, conic, stochastic and combinatorial optimization, are techniques for formulating and applying mathematical programming models, convex, nonsmooth and variational analysis, the theory of polyhedra, variational inequalities, and control and game theory viewed from the perspective of mathematical programming.