Showing papers on "Heuristic (computer science) published in 1971"

Experiments in mixed-integer linear programming

Abstract: This paper presents a “branch and bound” method for solving mixed integer linear programming problems. After briefly discussing the bases of the method, new concepts called pseudo-costs and estimations are introduced. Then, the heuristic rules for generating the tree, which are the main features of the method, are presented. Numerous parameters allow the user for adjusting the search strategy to a given problem.

A Functional Heuristic Algorithm for the Flowshop Scheduling Problem

Abstract: By exploiting the relationship between scheduling and sorting, this paper describes a functional heuristic algorithm for seeking a quick and approximate solution to the n-job, M-machine flo...

A man-machine approach toward solving the traveling salesman problem

Abstract: The traveling salesman problem, (form a circuit through N points with no subloops in such a way as to minimize the length of the circuit), is a close kin to many board wiring problems. It has been attacked by many mathematical methods with only meager results. Only for special forms of the problem or for problems with relatively few points can it be solved exactly even using very large amounts of computer time. Heuristic procedures have been proposed and tested with only slightly better results. This paper will describe a computer-aided heuristic technique which uses only a modest amount of computer time in real time to solve large (100-200) point problems. This technique takes advantage of both the computer's and the human's problem solving abilities. The computer is not asked to solve the problem in a brute force way as is the case in many of today's heuristics but it is asked to organize the data for the human in a fashion that allows the human to solve the problem easily.The techniques employed in this paper require that the computer and the human cooperate to find the solution to the problem in reasonable amounts of both of their times. The computer initially uses a series of heuristics that produce groups of points and some partial connections of these points. The human is asked to connect the points within the groups and then connect the groups in a manner that produces a circuit and appears to the human to maximize the ratio of enclosed area to perimeter. The computer takes this solution and uses another set of heuristics to make improvements. The solution is displayed to the human and if he is satisfied the procedure stops; if not the former procedure is repeated until the human is satisfied that cost for finding a better solution exceeds his estimate of the best possible improvement that could be obtained by further work. The heuristic procedures seek to group points around information obtained from solving a series of mathematical programming problems (assignment problems) and some observed correlations between these problems and the traveling salesman problem.The results are very good. The man-machine interaction solution for all problems in the literature is within one per cent of the solution for a fraction of the computer time. The experience to date indicates that the technique can be taught to inexperienced persons and their results, after training, are similar to those of the authors'.

A paradigm for reasoning by analogy

Abstract: A paradigm enabling heuristic problem solving programs to exploit an analogy between a current unsolved problem and a similar but previously solved problem to simplify its search for a solution is outlined. It is developed in detail for a first-order resolution logic theorem prover. Descriptions of the paradigm, implemented LISP programs, and preliminary experimental results are presented. This is believed to be the first system that develops analogical information and exploits it so that a problem-solving program can speed its search.

Optimal design of centralized computer networks

Abstract: Major design problems for centralized computer networks are link layout and capacity assignment. The objective is to select link locations and capacities so that the average time delay required to transmit a message from any node to the central node does not exceed a specified maximum. The design problem is to find the least cost system which satisfies the time delay constraints for given levels of traffic. In this paper, we describe an algorithm to select globally optimum link capacities for specified tree structures. We also give a heuristic method for finding low cost tree structures. The methods have been programmed and are capable of handling networks with thousands of nodes. In addition, they can consider any finite set of link capacities with an arbitrary cost structure and do not depend on the mathematical model used to calculate average time delay.

Automated placement of multi-terminal components

Abstract: An algorithm for placing multi-terminal electronic components in a printed circuit board environment is presented. A heuristic technique of applying vector forces to component models and iteratively relocating these modules has been developed. The methods used to compute these forces are what make this algorithm unique and improve its ability to find solutions that are independent of initial conditions and near optimal. A flexible modeling scheme has been devised to allow for any general class of components to be placed. The algorithm will place modules of arbitrary size with any number of terminals onto boards of irregular shape, including placement on two sides of a board. While most powerful in a printed circuit environment, the algorithm may be used in wire-wrap technologies and hybrid designs as well. The technique has been implemented in a Fortran program and exhibits the high degree of flexibility required in a design automation system. A summary of the results obtained in practical applications at Honeywell is included.

Optimal Multifunctional Material Systems

Abstract: Methods are presented for defining an optimal material system capable of controlling the environment within a structure. Too often in current practice each material element, called upon to perform a given function, such as structural support, sound or heat control, is specified independently. Currently each material element is designed to perform one function independent of the other elements. Efforts should be made to design interacting elements capable of performing more than one function, designated as a multifunctional material element. The methods are presented to aid in defining the optimal material system. These methods consist of user-oriented computer procedures for calculating the sound, heat, and structural characteristics of a stacked box structure. A special optimization procedure for handling multiobject function problems is presented, along with special heuristic features which can be used in conjunction with the optimization procedure.

A constrained maximum flow problem

Abstract: We consider the problem of maximizing the flow from one node to another in an oriented network subject to flow conservation and capacity limitation constraints and the additional constraint that for some nodes a certain positive linear combination of flows entering the node is bounded. Several properties of solutions to this problem are developed and a heuristic method for its solution is presented.

System for Heuristic and Rapid Processing of Component Layout and Wiring (SHARPCLAW)

Abstract: A computer-aided design system for layout of printed wiring boards is described, with emphasis on component placement and conductor routing algorithms. The system is designed to operate with a data base; placement and routing may be accomplished automatically using force field techniques and a maze-following procedure, or manually with extensive error checking by the computer. Examples of the system output are given.