We present approximation algorithms with O(n) processing time for the minimum vertex and edge guard problems in simple polygons. It is improved from previous O(n) time algorithms of Ghosh. For simple polygon, there are O(n) visibility regions, thus any approximation algorithm for the set covering problem with approximation ratio of log(n) can be used for the approximation of n vertex and edge g...

In this paper we identify various inaccuracies in the paper by R. R. Saxena and S. R. Arora, A Linearization technique for solving the Quadratic Set Covering Problem, Optimization, 39 (1997) 33-42. In particular, we observe that their algorithm does not guarantee optimality, contrary to what is claimed. Experimental analysis has been carried out to assess the value of this algorithm as a heuris...

We present a new Lagrangian-based heuristic for solving large-scale set-covering problems arising from crew-scheduling at the Italian Railways (Ferrovie dello Stato). Our heuristic obtained impressive results when compared to state of the art codes on a test-bed provided by the company, which includes instances with sizes ranging from 50,000 variables and 500 constraints to 1,000,000 variables ...

Abstract Database queries are one of the most important functions a relational database. Users interested in viewing variety data representations, and this may vary based on database purpose nature stored data. The Air Force Institute Technology has approximately 100 logs which will be converted to standardized Scorpion Data Model format. A is designed house its associated sensor non-sensor met...

The set covering problem is a classical problem in computer science and complexity theory and it serves as a model for many real-world applications especially in the resource allocation area. In an environment where the demands that need to be covered change over time, special methods are needed that adapt to such changes. We have developed an incremental clustering algorithm in order to addres...