VLSI cell placement problem is known to be NP complete. A wide repertoire of heuristic algorithms exists in the literature for efficiently arranging the logic cells on a VLSI chip. The objective of this paper is to present a comprehensive survey of the various cell placement techniques, with emphasis on standard ce11and macro

This paper reviews several problems that arise in the area of design automation. Most of these problems are shown to be NP-hard. Further, it is unlikely that any of these problems can be solved by fast approximation algorithms that guarantee solutions that are always within some fixed relative error of the optimal solution value. This points out the importance of heuristics and other tools to obtain algorithms that perform well on the problem instances of interest.

This paper presents an efficient heuristic algorithm for planning near-optimal high-level paths for a point agent moving through complex terrain modeled by the Weighted-Region Problem. The input to the Weighted-Region Problem is a set of non-overlapping convex polygonal homogeneous-cost regions on a two-dimensional plane. Each region has an associated cost coefficient (or weight), for the cost per unit distance of movement in that region by a point agent. The objective is to find a minimum-cost path through the weighted regions from a start point to a goal point. Our efficient algorithm combines heuristic search with probabilistic optimization by simulated annealing. It explores constrained random perturbations to the sequence of edges through which the path passes; then for each sequence, it solves a convex local-optimization subproblem to find the locally-optimal path and its cost. Extensive test results indicate that the new algorithm runs much faster than previously known technique...

The placement of records, and the methods used to access them, can significantly affect the performance of query processing in a database management system. By making use of information about query patterns and their frequencies, we aim to design file organisations which optimally cluster records through the use of indexes. Many different record indexing techniques can be used to cluster records. Multiattribute hash indexing is the indexing technique which we use to demonstrate the effectiveness of our proposals. We describe algorithms which exploit a clustering arrangement for range queries, join queries and other relational queries, and describe the costs of these algorithms. We compare the performance of various optimisation techniques for the problem of optimally clustering records using each of these algorithms. In general, designing optimal indexes to cluster records is NP-hard. We show that by combining heuristic and combinatorial algorithms, near-optimal indexes can be constru...

I hereby declare that I am the sole author of this thesis. I authorize the University of Guelph to lend this thesis to other institutions or individuals for the purpose of scholarly research. I further authorize the University of Guelph to reproduce this thesis by photo-copying or by other means, in total or in part, at the request of other institutions or individuals for the purpose of scholarly research. ii The University of Guelph requires the signatures of all persons using or photo-copying this thesis. Please sign below, and give address and date. iii iv A VLSI chip can today contain millions of transistors and is expected to contain more than 100 million transistors in the next decade. This tremendous growth is made possible by the development of sophisticated design tools and software. To deal with the complexity

In this paper we describe a general solution to the problem of optimal clustering of relations for a file which is to answer queries involving the join operation implemented using either the sort-merge or hash-join algorithms. This technique is extended to optimal clustering of relations when there are constraints on the domain size. In this paper we use the multi-attribute hashing technique as an indexing scheme to which our solution applies. Partially supported by an APRA scholarship. y Partially supported by a CRC/CIDS grant. 1 Introduction. Much work has been done in constructing schemes to cluster relations which optimise the performance of partial match queries. Determining the optimal clustering arrangement to minimise the average cost of a query is an area of research which has received some attention, primarily when the multi-attribute hashing indexing method is used. Examples of this may be found in [1, 14, 17, 21]. However, this form of retrieval is only one of the r...

The final purpose of Reactive Search Optimization (RSO) is to simplify the life for the final user of optimization. While researchers enjoy designing algorithms, testing alternatives, tuning parameters and choosing solution schemes — in fact this is part of their daily life — the final users ’ interests are different: solving a problem in the

We look at a possible alternative to designing parametric scenes through a traditional method by using a Genetic Selection of specific scenes in order to “evolve ” a solution which is acceptable to the user. We also show