Existentially restricted quantified constraint satisfaction

Quantified Constraint Satisfaction Problems (QCSP) are a generalization of Constraint Satisfaction Problems (CSP) in which variables may be quantified existentially and universally. QCSP offers a natural framework to express PSPACE problems as finite two-player games or planning under uncertainty. State-of-the-art QCSP solvers have an important drawback: they explore much larger combinatorial spaces than the natural search space of the original problem since they are unable to recognize that some sub-problems are necessarily true. We introduce a new tool, inspired by the cut rule of Prolog as a tool under responsibility of the designer of the QCSP, to prune those parts of the search space which are by construction known to be useless. We use this new tool to restore on one hand the annihilator property of true for disjunction in QCSP solver and, on the other hand, to prune the search space in two-player games. It is a simple solution to use efficiently QCSP to design finite two-player games without restricting the QCSP language. This tool does not need to modify the QCSP solver but has only one requirement: be able to tell the QCSP solver that the current QCSP is solved. Our QCSP solver built over Ge Code, a CSP library, obtained very good results compared to state-of-the-art QCSP solvers.

The constraint satisfaction probem (CSP) is a well-acknowledged framework in which many combinatorial search problems can be naturally formulated. The CSP may be viewed as the problem of deciding the truth of a logical sentence consisting of a conjunction of constraints, in front of which all variables are existentially quantified. The quantified constraint satisfaction problem (QCSP) is the generalization of the CSP where universal quantification is permitted in addition to existential quantification. The general intractability of these problems has motivated research studying the complexity of these problems under a restricted constraint language, which is a set of relations that can be used to express constraints. This paper introduces collapsibility, a technique for deriving positive complexity results on the QCSP. In particular, this technique allows one to show that, for a particular constraint language, the QCSP reduces to the CSP. We show that collapsibility applies to three known tractable cases of the QCSP that were originally studied using disparate proof techniques in different decades: Quantified 2-SAT (Aspvall, Plass, and Tarjan in 1979), Quantified Horn-SAT (Karpinski, Kleine Büning, and Schmitt in 1987), and Quantified Affine-SAT (Creignou, Khanna, and Sudan in 2001). This reconciles and reveals common structure among these cases, which are describable by constraint languages over a two-element domain. In addition to unifying these known tractable cases, we study constraint languages over domains of larger size.

The quantified constraint satisfaction problem (QCSP) is a natural and useful generalization of the constraint satisfaction problem (CSP) in which both universal and existential quantification of variables is permitted. Because the CSP and QCSP are in general intractable, much effort has been directed towards identifying restricted cases of these problems that are tractable in polynomial time. In this paper, we investigate restricted cases of the QCSP having 2-semilattice polymorphisms. We prove a complete classification of 2-semilattice polymorphisms, demonstrating that each gives rise to a case of the QCSP that is either tractable in polynomial time, or coNP-hard.

We consider the quantified constraint satisfaction problem (QCSP) which is to decide, given a structure and a first-order sentence (not assumed here to be in prenex form) built from conjunction and quantification, whether or not the sentence is true on the structure. We present a proof system for certifying the falsity of QCSP instances and develop its basic theory; for instance, we provide an algorithmic interpretation of its behavior. Our proof system places the established Q-resolution proof system in a broader context, and also allows us to derive QCSP tractability results.

Quantified Constraint Satisfaction Problems (QCSP) are often claimed to be adapted to model and solve problems such as twoplayer games, planning under uncertainty, and more generally problems in which the goal is to control a dynamic system subject to uncontrolled events. This paper shows that for a quite large class of such problems, using standard QCSP or QCSP+ is not the best approach. The main reasons are that in QCSP/QCSP+, (1) the underlying notion of system state is not explicitly taken into account, (2) problems are modeled over a bounded number of steps, and (3) algorithms search for winning strategies defined as memoryfull policy trees instead of winning strategies defined as memoryless mappings from states to decisions. This paper proposes a new constraint-based framework which does not suffer from these drawbacks. Experiments show orders of magnitude improvements when compared with QCSP/QCSP+ solvers.

In this article, the QCSP (Quantified Constraint Satisfaction Problems) framework is shifted to the QCHR (Quantified Constraint Handling Rules) framework by enabling dynamic generation of quantifiers and access to user-defined constraints. QCSP offers a natural framework to express PSPACE problems as finite two-players games. But to define a QCSP model, the alternation of quantifiers must be formerly known and cannot be built dynamically even if the worst case will not occur. To overcome this issue, the new QCHR formalism, that allows to generate quantifiers dynamically during the solving, is defined. QCHR models exhibit state-of-the-art performances on a priori fixed alternation of quantifiers and outperforms previous QCSP approaches when the generation of quantifiers is dynamic.

The Quantified Constraint Satisfaction Problem(QCSP) is a generalization of the classical constraint satisfaction problem in which some variables can be universally quantified. This additional expressiveness can help model problems in which a subset of the variables take value assignments that are outside the control of the decision maker. Typical examples of such domains are game-playing, conformant planning and reasoning under uncertainty. In these domains decision makers need explanations when a QCSP does not admit a winning strategy. We present an approach to defining preferences amongst the requirements of a QCSP, and an approach to finding most preferred explanations of inconsistency based on preferences over relaxations of quantifiers and constraints. This paper unifies work from the fields of constraint satisfaction, explanation generation, and reasoning under preferences and uncertainty.

This study focuses on the robust design optimization of permanent magnet linear synchronous motors (PMLSM) considering the effect of uncertainties (noise factors) such as manufacturing errors, installation errors and working wears. A robust design optimization approach based on quantified constraint satisfaction problem (QCSP) is proposed. It establishes a robust PMLSM thrust ripple model considering noise factors by QCSP, and obtains the optimal design parameters that have lower thrust ripple and smaller thrust ripple fluctuation within their error range by branch-and-prune algorithm. First, an analytical model of thrust ripple for PMLSM is established. Second, the robust QCSP model of thrust ripple is established by quantifier concept based on analytical model. It defines the design parameters and noise variables as existential and universal quantifiers, respectively, defines the variables of QCSP model as quantifier parameters that are composed of existential and universal quantifiers, then QCSP model are established by quantifier parameters. Third, the algorithm of branch-and-prune based on interval arithmetic is proposed to optimize the QCSP model. This approach is proven to be robust and superior compared with traditional deterministic approach and another robust approach. Finally, Finite element analysis and motor prototype experiments confirm the feasibility and validity of the proposed method.

In such as Real-time Scheduling Problems with uncertain interrupt operation, Quantified Constraint Satisfaction Problems were introduced to model and solve Constraint Satisfaction Problems involving uncertainty or uncontrollability on the value taken by some variables. In the former work, we propose to implement the schedulability test by using the algorithm QCSP-SchTest. In this paper, we analysis the search procedure in QCSP-SchTest and give a new algorithm QCSP-SchTest2 which combines the standard backtracking search with a repair-based procedure. A search state is best described as a strategy where we try to set the existential variables so that for all values of the universals there is a solution.

Worst-case and statistical tolerance analysis based on quantified constraint satisfaction problems and Monte Carlo simulation

Solving a quantified constraint satisfaction problem (QCSP) is usually a hard task due to its computational complexity. Exact algorithms play an important role in solving this problem, among which backtrack algorithms are effective. In a backtrack algorithm, an important step is assigning a variable by a chosen value when exploiting a branch, and thus a good value selection rule may speed up greatly. In this paper, we propose two value selection rules for existentially and universally quantified variables, respectively, to avoid unnecessary searching. The rule for universally quantified variables is prior to trying failure values in previous branches, and the rule for existentially quantified variables selects the promising values first. Two rules are integrated into the state-of-the-art QCSP solver, i.e., QCSP-Solve, which is an exact solver based on backtracking. We perform a number of experiments to evaluate improvements brought by our rules. From computational results, we can conclude that the new value selection rules speed up the solver by 5 times on average and 30 times at most. We also show both rules perform well particularly on instances with existentially and universally quantified variables occurring alternatively.

Many scholars researched social informatization from different perspectives, including profession, economy and technology. In this thesis, the author will studied on social informatization from the perspective of basic characteristics of information. Firstly, the author will describe other scholars’ social informationization theories. Secondly, the definition of information and basic characteristics of information will be given. Then, the production mode informatization and life-style informatization from the perspective of basic characteristics of information will be studied on in this paper. Lastly, the conclusion will be drawn.

The quantified constraint satisfaction probem (QCSP) is the problem of deciding, given a relational structure and a sentence consisting of a quantifier prefix followed by a conjunction of atomic formulas, whether or not the sentence is true in the structure. The general intractability of the QCSP has led to the study of restricted versions of this problem. In this article, we study restricted versions of the QCSP that arise from prespecifying the relations that may occur via a set of relations called a constraint language. A basic tool used is a correspondence that associates an algebra to each constraint language; this algebra can be used to derive information on the behavior of the constraint language. We identify a new combinatorial property on algebras, the polynomially generated powers(PGP) property, which we show is tightly connected to QCSP complexity. We also introduce another new property on algebras, switchability, which both implies the PGP property and implies positive complexity results on the QCSP. Our main result is a classification theorem on a class of three-element algebras: each algebra is either switchable and hence has the PGP, or provably lacks the PGP. The description of non-PGP algebras is remarkably simple and robust.

With the continuous improvement of China’s comprehensive national strength and the improvement of the level of social and economic development, people’s demand for science and technology is more urgent. In recent years, with the rapid development of information technology, computer technology has been gradually applied to art design. With the continuous popularization of technology, the role of this technology in the field of art has been gradually enhanced. This paper mainly analyzes and studies the positioning of computer technology in art design, the influence of computer technology on art design, and the application of this technology in art design. Therefore, it is recognized that the application of computer technology has brought new development vitality to the art design industry. Computer technology not only improves the limitation of traditional art design and production, but also helps the development of innovative art design industry. Through the research on the application of computer technology in art design, it is hoped that the relevant professional designers can further develop the application of computer technology in the field of art design and realize the qualitative leap of art design level.

Groundwater Monitoring & RemediationVolume 18, Issue 2 p. 68-72 In Situ Reactive Zones: Dehalogenation of Chlorinated Hydrocarbons Evan Nyer, Evan Nyer Evan K. Nyer is a vice president with ARCADIS Geraghty & Miller Inc., where he is responsible for maintaining and expanding the company's technical expertise in geology/hydrogeology, engineering, modeling, risk assessment, and bioremediation. He has been active in the development of new treatment technologies for many years. His areas of research interest include biological treatment, suspended solids separation, chemical oxidation, in situ treatment, air treatment systems, and the application of new technologies to ground water cleanup. He has been responsible for the strategies, technical design, and installation of more than 200 ground water and soil remediation systems at contaminated sites throughout the United States.Search for more papers by this authorFrank Lenzo, Frank Lenzo Evan K. Nyer is a vice president with ARCADIS Geraghty & Miller Inc., where he is responsible for maintaining and expanding the company's technical expertise in geology/hydrogeology, engineering, modeling, risk assessment, and bioremediation. He has been active in the development of new treatment technologies for many years. His areas of research interest include biological treatment, suspended solids separation, chemical oxidation, in situ treatment, air treatment systems, and the application of new technologies to ground water cleanup. He has been responsible for the strategies, technical design, and installation of more than 200 ground water and soil remediation systems at contaminated sites throughout the United States.Search for more papers by this authorJeffery Burdick, Jeffery Burdick Evan K. Nyer is a vice president with ARCADIS Geraghty & Miller Inc., where he is responsible for maintaining and expanding the company's technical expertise in geology/hydrogeology, engineering, modeling, risk assessment, and bioremediation. He has been active in the development of new treatment technologies for many years. His areas of research interest include biological treatment, suspended solids separation, chemical oxidation, in situ treatment, air treatment systems, and the application of new technologies to ground water cleanup. He has been responsible for the strategies, technical design, and installation of more than 200 ground water and soil remediation systems at contaminated sites throughout the United States.Search for more papers by this author Evan Nyer, Evan Nyer Evan K. Nyer is a vice president with ARCADIS Geraghty & Miller Inc., where he is responsible for maintaining and expanding the company's technical expertise in geology/hydrogeology, engineering, modeling, risk assessment, and bioremediation. He has been active in the development of new treatment technologies for many years. His areas of research interest include biological treatment, suspended solids separation, chemical oxidation, in situ treatment, air treatment systems, and the application of new technologies to ground water cleanup. He has been responsible for the strategies, technical design, and installation of more than 200 ground water and soil remediation systems at contaminated sites throughout the United States.Search for more papers by this authorFrank Lenzo, Frank Lenzo Evan K. Nyer is a vice president with ARCADIS Geraghty & Miller Inc., where he is responsible for maintaining and expanding the company's technical expertise in geology/hydrogeology, engineering, modeling, risk assessment, and bioremediation. He has been active in the development of new treatment technologies for many years. His areas of research interest include biological treatment, suspended solids separation, chemical oxidation, in situ treatment, air treatment systems, and the application of new technologies to ground water cleanup. He has been responsible for the strategies, technical design, and installation of more than 200 ground water and soil remediation systems at contaminated sites throughout the United States.Search for more papers by this authorJeffery Burdick, Jeffery Burdick Evan K. Nyer is a vice president with ARCADIS Geraghty & Miller Inc., where he is responsible for maintaining and expanding the company's technical expertise in geology/hydrogeology, engineering, modeling, risk assessment, and bioremediation. He has been active in the development of new treatment technologies for many years. His areas of research interest include biological treatment, suspended solids separation, chemical oxidation, in situ treatment, air treatment systems, and the application of new technologies to ground water cleanup. He has been responsible for the strategies, technical design, and installation of more than 200 ground water and soil remediation systems at contaminated sites throughout the United States.Search for more papers by this author First published: 22 February 2007 https://doi.org/10.1111/j.1745-6592.1998.tb00616.xCitations: 2AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume18, Issue2May 1998Pages 68-72 RelatedInformation