896 research outputs found
Optimal Point Placement for Mesh Smoothing
We study the problem of moving a vertex in an unstructured mesh of
triangular, quadrilateral, or tetrahedral elements to optimize the shapes of
adjacent elements. We show that many such problems can be solved in linear time
using generalized linear programming. We also give efficient algorithms for
some mesh smoothing problems that do not fit into the generalized linear
programming paradigm.Comment: 12 pages, 3 figures. A preliminary version of this paper was
presented at the 8th ACM/SIAM Symp. on Discrete Algorithms (SODA '97). This
is the final version, and will appear in a special issue of J. Algorithms for
papers from SODA '9
Quasiconvex Programming
We define quasiconvex programming, a form of generalized linear programming
in which one seeks the point minimizing the pointwise maximum of a collection
of quasiconvex functions. We survey algorithms for solving quasiconvex programs
either numerically or via generalizations of the dual simplex method from
linear programming, and describe varied applications of this geometric
optimization technique in meshing, scientific computation, information
visualization, automated algorithm analysis, and robust statistics.Comment: 33 pages, 14 figure
Audit Games with Multiple Defender Resources
Modern organizations (e.g., hospitals, social networks, government agencies)
rely heavily on audit to detect and punish insiders who inappropriately access
and disclose confidential information. Recent work on audit games models the
strategic interaction between an auditor with a single audit resource and
auditees as a Stackelberg game, augmenting associated well-studied security
games with a configurable punishment parameter. We significantly generalize
this audit game model to account for multiple audit resources where each
resource is restricted to audit a subset of all potential violations, thus
enabling application to practical auditing scenarios. We provide an FPTAS that
computes an approximately optimal solution to the resulting non-convex
optimization problem. The main technical novelty is in the design and
correctness proof of an optimization transformation that enables the
construction of this FPTAS. In addition, we experimentally demonstrate that
this transformation significantly speeds up computation of solutions for a
class of audit games and security games
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