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CBACK - A SIMPLE TOOL FOR backtrack programming IN C

SOFTWARE-PRACTICE & EXPERIENCE 1995年第8期25卷 905-934页

作者： HELSGAUN, K Department of Computer Science Roskilde University DK-4000 Roskilde Denmark

backtrack programming is such a powerful technique for problem solving that a number of languages, especially in the area of artificial intelligence, have built-in facilities for backtrack programming. This paper describes CBack, a simple, but general tool for backtrack programming in the programming language C. The use of the tool is illustrated through examples of a tutorial nature. In addition to the usual depth-first search strategy, CBack provides for the more general heuristic best-first search strategy. The implementation of CBack is described in detail. The source code, shown in its full length, is entirely written in ANSI C and highly portable across diverse computer architectures and C compilers.

关键词： backtrack programming backtrackING C programming LANGUAGES

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AN ALGORITHM FOR EXHAUSTIVE GENERATION OF BUILDING FLOOR PLANS

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COMMUNICATIONS OF THE ACM 1981年第12期24卷 813-825页

作者： GALLE, P Nordisk Kollegium Denmark

The combinatorial complexity of most floor plan design problems makes it practically impossible to obtain a systematic knowledge of possible solutions using pencil and paper. The objective of this paper is to contribute to the development of computer methods providing such knowledge for the designer. The paper describes an algorithm which generates all possible rectangular plans on modular grids with congruent cells, subject to constraints on total area, room areas, wall lengths, room adjacencies, and room orientations. To make room sizes regular and limit the solution set only such grids are used which minimize the number of cells in the smallest room. The description is sufficiently detailed to serve as a basis for programming. Test results for a Pascal implementation of the algorithm are reported. Realistic problems of up to ten rooms have been solved in modest lengths of computer time. The results indicate that the approach of exhaustive generation may prove to be more fruitful than generally assumed.

关键词： architecture automated design backtrack programming combinatorial programming exhaustive tree search floor plans space planning

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PACKED SCATTER TABLES

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COMMUNICATIONS OF THE ACM 1978年第10期21卷 857-865页

作者： LYON, G National Bureau of Standards Washington DC

Scatter tables for open addressing benefit from recursive entry displacements, cutoffs for unsuccessful searches, and auxiliary cost functions. Compared with conventional methods, the new techniques provide substantially improved tables that resemble exact-solution optimal packings. The displacements are depth-limited approximations to an enumerative (exhaustive) optimization, although packing costs remain linear—O(n)—with table size n. The techniques are primarily suited for important fixed (but possibly quite large) tables for which reference frequencies may be known: op-code tables, spelling dictionaries, access arrays. Introduction of frequency weights further improves retrievals, but the enhancement may degrade cutoffs.

关键词： assignment problem backtrack programming hashing open addressing recursion scatter table rearrangements

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Developing Heuristic for Subgraph Isomorphism Problem

Developing Heuristic for Subgraph Isomorphism Problem

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5th International Conference on Contemporary Computing

作者： Kaijar, Saifuddin Bhavani, S. Durga Univ Hyderabad Dept Comp & Informat Sci Hyderabad 500134 Andhra Pradesh India

ISBN: (纸本)9783642321283

Subgraph isomorphism problem is an NP-hard problem and the available algorithms are of exponential time complexity. Hence these are not efficient for real world applications. A number of heuristic methods are proposed in the literature in this field. Ullmann[6] proposed a solution for subgraph isomorphism problem in 1976, which is being referred till today. Ullmann's algorithm is refined to get better algorithms in current literature. Cordella et al.[7] proposed an algorithm VF2, that improves Ullmann's refinement. In this project, we propose a heuristic to be applied to Ullmann's algorithm in order to reduce the search space. We show that the proposed heuristic performs better than both Ullmann's and VF2 algorithm. The testing is done using a graph generation software[12]. Further the heuristic algorithm is tested on the benchmark data set [4]. Both the experiments show that our proposed heuristics perform better for all type of graphs given in the benchmark data set.

关键词： backtrack programming graph similarity measure isomorphism graph matching

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A backtrack Procedure for Isomorphism of Directed Graphs

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Journal of the ACM (JACM) 1973年第3期20卷 365-377页

作者： Berztiss, A.T. University of Pittsburgh Department of Computer Science Pittsburgh Pennsylvania 12560 United States

A reasonably efficient procedure for testing pairs of directed graphs for isomorphism is important in information retrieval and other application fields in which structured data have to be matched. One such procedure, a backtrack procedure based on a representation of directed graphs by linear formulas, is described. A procedure for finding a partial subdigraph of a digraph that is isomorphic to a given digraph is also described. © 1973, ACM. All rights reserved.

关键词： backtrack programming digraph isomorphism representation of digraphs

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A Fast backtracking Algorithm to Test Directed Graphs for Isomorphism Using Distance Matrices

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Journal of the ACM (JACM) 1976年第3期23卷 433-445页

作者： Schmidt, Douglas C. Druffel, Larry E. Systems and Information Science Department Vanderbilt University Nashville TN 37235 Box 6146 Station B United States Department of Astronautics and Computer Science United States Air Force Academy CO 80840 United States

A backtracking algorithm for testing a pair of digraphs for isomorphism is presented. The information contained in the distance matrix representation of a graph is used to establish an initial partition of the graph's vertices. This distance matrix information is then applied in a backtracking procedure to reduce the search tree of possible mappings. While the algorithm is not guaranteed to run in polynomial time, it performs efficiently for a large class of graphs. © 1976, ACM. All rights reserved.

关键词： backtrack programming digraph distance matrix momorphlsm partltmnmg CR CATEGORIES 532

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The specification of program flow in Madcap 6 72

The specification of program flow in Madcap 6

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1972 ACM Annual Conference/Annual Meeting, ACM 1972

作者： Morris, James B. Wells, Mark B. Los Alamos Scientific Laboratory University of California United States

ISBN: (纸本)9781450374927

The control structures of the Madcap language have evolved to a point where today those of Madcap 6 have obviated programmer defined labels and go-to statements. The benefits of the removal of these concepts are discussed in detail. Madcap has a powerful class of data structures, including sets, sequences, and expressions, along with a full array of operators for manipulating these structures. These operators include important facilities for forming sets and for forming and concatenating sequences, based on very general iterative expressions. Procedures in Madcap are expressions whose evaluation is deferred;characteristics of this approach are discussed. Also described is a notation which facilitates backtrack programming. © 1972 Association for Computing Machinery Inc. All rights reserved.

关键词： Program flow Recursive procedures Madcap Iterative expressions backtrack programming Go-to removal Control structures Expression language Conditional expressions Two-dimensional language Set theory Co-routines Programmer defined labels Bliss

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