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Towards an understanding of hillclimbing procedures for SAT
 In Proceedings of AAAI93
, 1993
"... Recently several local hillclimbing procedures for propositional satisability havebeen proposed, which are able to solve large and di cult problems beyond the reach ofconventional algorithms like DavisPutnam. By the introduction of some new variants of these procedures, we provide strong experimen ..."
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Cited by 137 (6 self)
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Recently several local hillclimbing procedures for propositional satisability havebeen proposed, which are able to solve large and di cult problems beyond the reach ofconventional algorithms like DavisPutnam. By the introduction of some new variants of these procedures, we provide strong experimental evidence to support the conjecture that neither greediness nor randomness is important in these procedures. One of the variants introduced seems to o er signi cant improvements over earlier procedures. In addition, we investigate experimentally how their performance depends on their parameters. Our results suggest that runtime scales less than simply exponentially in the problem size. 1
Automatic SATCompilation of Planning Problems
 IJCAI97
, 1997
"... Recent work by Kautz et al. provides tantalizing evidence that large, classical planning problems may be efficiently solved by translating them into propositional satisfiability problems, using stochastic search techniques, and translating the resulting truth assignments back into plans for the ..."
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Cited by 121 (10 self)
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Recent work by Kautz et al. provides tantalizing evidence that large, classical planning problems may be efficiently solved by translating them into propositional satisfiability problems, using stochastic search techniques, and translating the resulting truth assignments back into plans for the original problems. We explore the space of such transformations, providing a simple framework that generates eight major encodings (generated by selecting one of four action representations and one of two frame axioms) and a number of subsidiary ones. We describe a fullyimplemented compiler that can generate each of these encodings, and we test the compiler on a suite of STRIPS planning problems in order to determine which encodings have the best properties.
Recent Advances in AI Planning
 AI MAGAZINE
, 1999
"... The past five years have seen dramatic advances in planning algorithms, with an emphasis on propositional methods such as Graphplan and compilers that convert planning problems into propositional CNF formulae for solution via systematic or stochastic SAT methods. Related work on the Deep Space O ..."
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Cited by 108 (0 self)
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The past five years have seen dramatic advances in planning algorithms, with an emphasis on propositional methods such as Graphplan and compilers that convert planning problems into propositional CNF formulae for solution via systematic or stochastic SAT methods. Related work on the Deep Space One spacecraft control algorithms advances our understanding of interleaved planning and execution. In this survey,we explain the latest techniques and suggest areas for future research.
A Comprehensive Framework For Testing Graphical User Interfaces
, 2001
"... ... This thesis develops a unified solution to the GUI testing problem with the particular goals of automation and integration of tools and techniques used in various phases of GUI testing. These goals are accomplished by developing a GUI testing framework with a GUI model as its central component. ..."
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Cited by 35 (7 self)
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... This thesis develops a unified solution to the GUI testing problem with the particular goals of automation and integration of tools and techniques used in various phases of GUI testing. These goals are accomplished by developing a GUI testing framework with a GUI model as its central component. For efficiency and scalability, a GUI is represented as a hierarchy of components, each used as a basic unit of testing. The framework also includes a test coverage evaluator, test case generator, test oracle, test executor, and regression tester. The test coverage evaluator employs hierarchical, eventbased coverage criteria to automatically specify what to test in a GUI and to determine whether the test suite has adequately tested the GUI. The test case generator employs plan generation techniques from artificial intelligence to automatically generate a test suite. A test executor automatically executes all the test cases on the GUI. As test cases are being executed, a test oracle automatically determines the correctness of the GUI. The test oracle employs a model of the expected state of the GUI in terms of its constituent objects and their properties. After changes are made to a GUI, a regression tester partitions the original GUI test suite into valid test cases that represent correct input/output for the modified GUI and invalid test cases that no longer represent correct input/output. The regression tester employs a new technique to reuse some of the invalid test cases by repairing them.
ConflictDirected Backjumping Revisited
, 2001
"... In recent years, many improvements to backtracking algorithms for solving constraint satisfaction problems have been proposed. The techniques for improving backtracking algorithms can be conveniently classified as lookahead schemes and lookback schemes. Unfortunately, lookahead and lookback sche ..."
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Cited by 28 (1 self)
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In recent years, many improvements to backtracking algorithms for solving constraint satisfaction problems have been proposed. The techniques for improving backtracking algorithms can be conveniently classified as lookahead schemes and lookback schemes. Unfortunately, lookahead and lookback schemes are not entirely orthogonal as it has been observed empirically that the enhancement of lookahead techniques is sometimes counterproductive to the effects of lookback techniques. In this paper, we focus on the relationship between the two most important lookahead techniques  using a variable ordering heuristic and maintaining a level of local consistency during the backtracking search  and the lookback technique of conflictdirected backjumping (CBJ). We show that there exists a "perfect" dynamic variable ordering such that CBJ becomes redundant. We also show theoretically that as the level of local consistency that is maintained in the backtracking search is increased, the less that backjumping will be an improvement. Our theoretical results partially explain why a backtracking algorithm doing more in the lookahead phase cannot benefit more from the backjumping lookback scheme. Finally, we show empirically that adding CBJ to a backtracking algorithm that maintains generalized arc consistency (GAC), an algorithm that we refer to as GACCBJ, can still provide orders of magnitude speedups. Our empirical results contrast with Bessiere and Regin's conclusion (1996) that CBJ is useless to an algorithm that maintains arc consistency.
Applying GSAT to NonClausal Formulas
 JOURNAL OF ARTIFICIAL INTELLIGENCE RESEARCH
, 1994
"... In this paper we describe how to modify GSAT so that it can be applied to nonclausal formulas. The idea is to use a function which computes the number of clauses of the CNF conversion of a formula which are false under a certain truth assignment, without constructing the conversion itself. The prop ..."
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Cited by 19 (3 self)
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In this paper we describe how to modify GSAT so that it can be applied to nonclausal formulas. The idea is to use a function which computes the number of clauses of the CNF conversion of a formula which are false under a certain truth assignment, without constructing the conversion itself. The proposed methodology applies to most variants of GSAT.
Parallel cooperative propositional theorem proving
 Annals of Mathematics and Artificial Intelligence
, 1998
"... A parallel satis ability testing algorithm called Parallel Modoc is presented. Parallel Modoc is based on Modoc, which is based on propositional Model Elimination with an added capability to prune away certain branches that cannot lead to a successful subrefutation. The pruning information is encod ..."
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Cited by 13 (3 self)
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A parallel satis ability testing algorithm called Parallel Modoc is presented. Parallel Modoc is based on Modoc, which is based on propositional Model Elimination with an added capability to prune away certain branches that cannot lead to a successful subrefutation. The pruning information is encoded in a partial truth assignment called an autarky. Parallel Modoc executes multiple instances of Modoc as separate processes and allows processes to cooperate by sharing lemmas and autarkies as they are found. When a Modoc process nds a new autarky or a new lemma, it makes the information available to other Modoc processes via a \blackboard". Combining autarkies generally is not straightforward because two autarkies found by two separate processes may have con icting assignments. The paper presents an algorithm to combine two arbitrary autarkies to form a larger autarky. Experimental results show that for many of the formulas, Parallel Modoc achieves speedup greater than the number of processors. Formulas that could not be solved in an hour by Modoc were often solved by Parallel Modoc in the order of minutes, and in some cases, in seconds.
Boundary Region Relations
, 1998
"... We are interested in the problem of how an agent organizes its sensorimotor experiences in order to create a spatial representation. Our approachto solve this problem is the Spatial Semantic Hierarchy #SSH#, where multiple levels of spatial representation coexists. At the SSH topological level, ..."
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Cited by 5 (4 self)
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We are interested in the problem of how an agent organizes its sensorimotor experiences in order to create a spatial representation. Our approachto solve this problem is the Spatial Semantic Hierarchy #SSH#, where multiple levels of spatial representation coexists. At the SSH topological level, space is represented by places and connectivity relation among them. Places are arranged into streets so that the topological representation looks like the street network of a city.
Planning as Model Construction in Linear Temporal Logic
, 1997
"... In this work we propose a logical approach to planning, based on the view of a planning activity as the search for a finite model of the specification of the planning problem. Planning problems are represented in a modal temporal language, based on a discrete, linear model of time, whose execution m ..."
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Cited by 1 (1 self)
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In this work we propose a logical approach to planning, based on the view of a planning activity as the search for a finite model of the specification of the planning problem. Planning problems are represented in a modal temporal language, based on a discrete, linear model of time, whose execution mechanism exploits model construction techniques related to analytic tableaux. The tableau system is based on the use of prefixes that, intuitively, label each formula as being true in a particular state. This approach allows the exploitation of methods and results from searchbased approaches, such as planspace search, regression and least commitment. A partial ordering of time points is in fact allowed in the calculus, by means of a set of temporal constraints that is built up step by step as the construction of a tableau branch proceeds. A form of soundness and completeness with respect to finite model construction are established, constituting the grounds for a decision procedure that is parametric w.r.t. the maximal time length a plan is allowed to reach.
Modification Strategies for SATbased Plan Adaptation
, 2008
"... Planning, the generation of a course of action to achieve a set of goals, is an important technique in the development of intelligent agents. Heretofore, planning has been largely considered as a oneshot problem. However, in practice, we are often dealing with situations in which an existing plan h ..."
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Planning, the generation of a course of action to achieve a set of goals, is an important technique in the development of intelligent agents. Heretofore, planning has been largely considered as a oneshot problem. However, in practice, we are often dealing with situations in which an existing plan has to be adapted. Not only might we be facing a dynamic environment that requires a plan to be repaired, but it may also be that we recognise the new planning problem as being similar to one that we have solved before (i.e. casebased planning). This paper investigates a plan adaptation framework based on SATencodings of the planning problem. Compilation techniques have been very successfully applied to planning, as evidenced by their success in recent planning competitions. So far, however, such techniques have not been used for plan adaptation purposes. This paper explores whether it is feasible to modify the generated SAT instances such as to encode information that was extracted from the solution to the original planning problem.