The Experts below are selected from a list of 24273 Experts worldwide ranked by ideXlab platform
Dietrich Kuske - One of the best experts on this subject based on the ideXlab platform.
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uniform Satisfiability Problem for local temporal logics over mazurkiewicz traces
Information & Computation, 2010Co-Authors: Paul Gastin, Dietrich KuskeAbstract:We continue our study of the complexity of MSO-definable local temporal logics over concurrent systems that can be described by Mazurkiewicz traces. In previous papers, we showed that the Satisfiability Problem for any such logic is in PSPACE (provided the dependence alphabet is fixed, Gastin and Kuske (2003) [10]) and remains in PSPACE for all classical local temporal logics even if the dependence alphabet is part of the input, Gastin and Kuske (2007) [8]. In this paper, we consider the uniform Satisfiability Problem for arbitrary MSO-definable local temporal logics. For this Problem, we prove multi-exponential lower and upper bounds that depend on the number of alternations of set quantifiers present in the chosen MSO-modalities.
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Uniform Satisfiability Problem for local temporal logics over Mazurkiewicz traces
Information and Computation, 2010Co-Authors: Paul Gastin, Dietrich KuskeAbstract:We continue our study of the complexity of MSO-definable local temporal logics over concurrent systems that can be described by Mazurkiewicz traces. In previous papers, we showed that the Satisfiability Problem for any such logic is in PSPACE (provided the dependence alphabet is fixed) and remains in PSPACE for all classical local temporal logics even if the dependence alphabet is part of the input. In this paper, we consider the uniform Satisfiability Problem for arbitrary MSO-definable local temporal logics. For this Problem, we prove multi-exponential lower and upper bounds that depend on the number of alternations of set quantifiers present in the chosen MSO-modalities.
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uniform Satisfiability Problem for local temporal logics over mazurkiewicz traces
International Conference on Concurrency Theory, 2005Co-Authors: Paul Gastin, Dietrich KuskeAbstract:We continue our study of the complexity of temporal logics over concurrent systems that can be described by Mazurkiewicz traces. In a previous paper (CONCUR 2003), we investigated the class of local and MSO definable temporal logics that capture all known temporal logics and we showed that the Satisfiability Problem for any such logic is in PSPACE (provided the dependence alphabet is fixed). In this paper, we concentrate on the uniform Satisfiability Problem: we consider the dependence alphabet (i.e., the architecture of the distributed system) as part of the input. We prove lower and upper bounds for the uniform Satisfiability Problem that depend on the number of monadic quantifier alternations present in the chosen MSO-modalities.
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CONCUR - Uniform Satisfiability Problem for local temporal logics over Mazurkiewicz traces
Lecture Notes in Computer Science, 2005Co-Authors: Paul Gastin, Dietrich KuskeAbstract:We continue our study of the complexity of temporal logics over concurrent systems that can be described by Mazurkiewicz traces. In a previous paper (CONCUR 2003), we investigated the class of local and MSO definable temporal logics that capture all known temporal logics and we showed that the Satisfiability Problem for any such logic is in PSPACE (provided the dependence alphabet is fixed). In this paper, we concentrate on the uniform Satisfiability Problem: we consider the dependence alphabet (i.e., the architecture of the distributed system) as part of the input. We prove lower and upper bounds for the uniform Satisfiability Problem that depend on the number of monadic quantifier alternations present in the chosen MSO-modalities.
Paul Gastin - One of the best experts on this subject based on the ideXlab platform.
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uniform Satisfiability Problem for local temporal logics over mazurkiewicz traces
Information & Computation, 2010Co-Authors: Paul Gastin, Dietrich KuskeAbstract:We continue our study of the complexity of MSO-definable local temporal logics over concurrent systems that can be described by Mazurkiewicz traces. In previous papers, we showed that the Satisfiability Problem for any such logic is in PSPACE (provided the dependence alphabet is fixed, Gastin and Kuske (2003) [10]) and remains in PSPACE for all classical local temporal logics even if the dependence alphabet is part of the input, Gastin and Kuske (2007) [8]. In this paper, we consider the uniform Satisfiability Problem for arbitrary MSO-definable local temporal logics. For this Problem, we prove multi-exponential lower and upper bounds that depend on the number of alternations of set quantifiers present in the chosen MSO-modalities.
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Uniform Satisfiability Problem for local temporal logics over Mazurkiewicz traces
Information and Computation, 2010Co-Authors: Paul Gastin, Dietrich KuskeAbstract:We continue our study of the complexity of MSO-definable local temporal logics over concurrent systems that can be described by Mazurkiewicz traces. In previous papers, we showed that the Satisfiability Problem for any such logic is in PSPACE (provided the dependence alphabet is fixed) and remains in PSPACE for all classical local temporal logics even if the dependence alphabet is part of the input. In this paper, we consider the uniform Satisfiability Problem for arbitrary MSO-definable local temporal logics. For this Problem, we prove multi-exponential lower and upper bounds that depend on the number of alternations of set quantifiers present in the chosen MSO-modalities.
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uniform Satisfiability Problem for local temporal logics over mazurkiewicz traces
International Conference on Concurrency Theory, 2005Co-Authors: Paul Gastin, Dietrich KuskeAbstract:We continue our study of the complexity of temporal logics over concurrent systems that can be described by Mazurkiewicz traces. In a previous paper (CONCUR 2003), we investigated the class of local and MSO definable temporal logics that capture all known temporal logics and we showed that the Satisfiability Problem for any such logic is in PSPACE (provided the dependence alphabet is fixed). In this paper, we concentrate on the uniform Satisfiability Problem: we consider the dependence alphabet (i.e., the architecture of the distributed system) as part of the input. We prove lower and upper bounds for the uniform Satisfiability Problem that depend on the number of monadic quantifier alternations present in the chosen MSO-modalities.
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CONCUR - Uniform Satisfiability Problem for local temporal logics over Mazurkiewicz traces
Lecture Notes in Computer Science, 2005Co-Authors: Paul Gastin, Dietrich KuskeAbstract:We continue our study of the complexity of temporal logics over concurrent systems that can be described by Mazurkiewicz traces. In a previous paper (CONCUR 2003), we investigated the class of local and MSO definable temporal logics that capture all known temporal logics and we showed that the Satisfiability Problem for any such logic is in PSPACE (provided the dependence alphabet is fixed). In this paper, we concentrate on the uniform Satisfiability Problem: we consider the dependence alphabet (i.e., the architecture of the distributed system) as part of the input. We prove lower and upper bounds for the uniform Satisfiability Problem that depend on the number of monadic quantifier alternations present in the chosen MSO-modalities.
Lenka Zdeborová - One of the best experts on this subject based on the ideXlab platform.
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Adversarial Satisfiability Problem
Journal of Statistical Mechanics: Theory and Experiment, 2011Co-Authors: Michele Castellana, Lenka ZdeborováAbstract:We study the adversarial Satisfiability Problem, where the adversary can choose whether the variables are negated in clauses or not, in order to make the resulting formula unsatisfiable. This Problem belongs to a general class of adversarial optimization Problems that often arise in practice and are algorithmically much harder than the standard optimization Problems. We use the cavity method to compute large deviations of the entropy in the random Satisfiability Problem with respect to the configurations of negations. We conclude that in the thermodynamic limit the best strategy the adversary can adopt is to simply balance the number of times every variable is negated and the number of times it is not negated. We also conduct a numerical study of the Problem, and find that there are very strong pre-asymptotic effects that may be due to the fact that for small sizes exponential and factorial growth is hardly distinguishable. As a side result we compute the Satisfiability threshold for balanced configurations of negations, and also the random regular Satisfiability, i.e. when all variables belong to the same number of clauses.
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Adversarial Satisfiability Problem
Journal of Statistical Mechanics: Theory and Experiment, 2011Co-Authors: Michele Castellana, Lenka ZdeborováAbstract:We study the adversarial Satisfiability Problem, where the adversary can choose whether variables are negated in clauses or not in order to make the resulting formula unsatisfiable. This is one case of a general class of adversarial optimization Problems that often arise in practice and are algorithmically much harder than the standard optimization Problems. We use the cavity method to compute large deviations of the entropy in the random Satisfiability Problem with respect to the negation-configurations. We conclude that in the thermodynamic limit the best strategy the adversary can adopt is extremely close to simply balancing the number of times every variable is and is not negated. We also conduct a numerical study of the Problem, and find that there are very strong pre-asymptotic effects that are due to the fact that for small sizes exponential and factorial growth is hardly distinguishable.
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exhaustive enumeration unveils clustering and freezing in the random 3 Satisfiability Problem
Physical Review E, 2008Co-Authors: John Ardelius, Lenka ZdeborováAbstract:We study geometrical properties of the complete set of solutions of the random 3-Satisfiability Problem. We show that even for moderate system sizes the number of clusters corresponds surprisingly well with the theoretic asymptotic prediction. We locate the freezing transition in the space of solutions, which has been conjectured to be relevant in explaining the onset of computational hardness in random constraint satisfaction Problems.
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phase diagram of the 1 in 3 Satisfiability Problem
Physical Review E, 2007Co-Authors: Jack Raymond, Andrea Sportiello, Lenka ZdeborováAbstract:We study typical case properties of the 1-in-3 Satisfiability Problem, the Boolean satisfaction Problem, where a clause is satisfied by exactly one literal, in an enlarged random ensemble parametrized by average connectivity and probability of negation of a variable in a clause. Random 1-in-3 Satisfiability and exact 3-cover are special cases of this ensemble. We interpolate between these cases from a region where Satisfiability can be typically decided for all connectivities in polynomial time to a region where deciding Satisfiability is hard, in some interval of connectivities. We derive several rigorous results in the first region and develop a one-step replica-symmetry-breaking cavity analysis in the second one. We discuss the prediction for the transition between the almost surely satisfiable and the almost surely unsatisfiable phase, and other structural properties of the phase diagram, in light of cavity method results.
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The Phase Diagram of 1-in-3 Satisfiability Problem
Physical Review E : Statistical Nonlinear and Soft Matter Physics, 2007Co-Authors: Jack Raymond, Andrea Sportiello, Lenka ZdeborováAbstract:We study the typical case properties of the 1-in-3 Satisfiability Problem, the boolean satisfaction Problem where a clause is satisfied by exactly one literal, in an enlarged random ensemble parametrized by average connectivity and probability of negation of a variable in a clause. Random 1-in-3 Satisfiability and Exact 3-Cover are special cases of this ensemble. We interpolate between these cases from a region where Satisfiability can be typically decided for all connectivities in polynomial time to a region where deciding Satisfiability is hard, in some interval of connectivities. We derive several rigorous results in the first region, and develop the one-step--replica-symmetry-breaking cavity analysis in the second one. We discuss the prediction for the transition between the almost surely satisfiable and the almost surely unsatisfiable phase, and other structural properties of the phase diagram, in light of cavity method results.
Jason Crampton - One of the best experts on this subject based on the ideXlab platform.
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the bi objective workflow Satisfiability Problem and workflow resiliency
Journal of Computer Security, 2017Co-Authors: Jason Crampton, Gregory Gutin, Daniel Karapetyan, Remi WatrigantAbstract:A computerized workflow management system may enforce a security policy, specified in terms of authorized actions and constraints, thereby restricting which users can perform particular steps in a workflow. The existence of a security policy may mean that a workflow is unsatisfiable, in the sense that it is impossible to find a valid plan (an assignment of steps to authorized users such that all constraints are satisfied). Work in the literature focuses on the workflow Satisfiability Problem, a decision Problem that outputs a valid plan if the instance is satisfiable (and a negative result otherwise). In this paper, we introduce the Bi-Objective Workflow Satisfiability Problem (BO-WSP), which enables us to solve optimization Problems related to workflows and security policies. In particular, we are able to compute a “least bad” plan when some components of the security policy may be violated. In general, BO-WSP is intractable from both the classical and parameterized complexity point of view (where the parameter is the number of steps). We prove that computing a Pareto front for BO-WSP is fixed-parameter tractable (FPT) if we restrict our attention to user-independent constraints. This result has important practical consequences, since most constraints of practical interest in the literature are user-independent. Our proof is constructive and defines an algorithm, the implementation of which we describe and evaluate. We also present a second algorithm to compute a Pareto front which solves multiples instances of a related Problem using mixed integer programming (MIP). We compare the performance of both our algorithms on synthetic instances, and show that the FPT algorithm outperforms the MIP-based one by several orders of magnitude on most instances. Finally, we study the important question of workflow resiliency and prove new results establishing that known decision Problems are fixed-parameter tractable when restricted to user-independent constraints. We then propose a new way of modeling the availability of users and demonstrate that many questions related to resiliency in the context of this new model may be reduced to instances of BO-WSP.
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the bi objective workflow Satisfiability Problem and workflow resiliency
arXiv: Cryptography and Security, 2015Co-Authors: Jason Crampton, Gregory Gutin, Daniel Karapetyan, Remi WatrigantAbstract:A computerized workflow management system may enforce a security policy, specified in terms of authorized actions and constraints, thereby restricting which users can perform particular steps in a workflow. The existence of a security policy may mean it is impossible to find a valid plan (an assignment of steps to authorized users such that all constraints are satisfied). Work in the literature focuses on the workflow Satisfiability Problem, a \emph{decision} Problem that outputs a valid plan if the instance is satisfiable (and a negative result otherwise). In this paper, we introduce the \textsc{Bi-Objective Workflow Satisfiability Problem} (\BOWSP), which enables us to solve \emph{optimization} Problems related to workflows and security policies. In particular, we are able to compute a "least bad" plan when some components of the security policy may be violated. In general, \BOWSP is intractable from both the classical and parameterized complexity point of view. We prove there exists an fixed-parameter tractable (FPT) algorithm to compute a Pareto front for \BOWSP if we restrict our attention to user-independent constraints. We also present a second algorithm to compute a Pareto front which uses mixed integer programming (MIP). We compare the performance of both our algorithms on synthetic instances, and show that the FPT algorithm outperforms the MIP-based one by several orders of magnitude on most of the instances. Finally, we study the important question of workflow resiliency and prove new results establishing that known decision Problems are fixed-parameter tractable when restricted to user-independent constraints. We then propose a new way of modeling the availability of users and demonstrate that many questions related to resiliency in the context of this new model may be reduced to instances of \BOWSP.
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valued workflow Satisfiability Problem
Symposium on Access Control Models and Technologies, 2015Co-Authors: Jason Crampton, Gregory Gutin, Daniel KarapetyanAbstract:A workflow is a collection of steps that must be executed in some specific order to achieve an objective. A computerised workflow management system may enforce authorisation policies and constraints, thereby restricting which users can perform particular steps in a workflow. The existence of policies and constraints may mean that a workflow is unsatisfiable, in the sense that it is impossible to find an authorised user for each step in the workflow and satisfy all constraints. In this paper, we consider the Problem of finding the "least bad" assignment of users to workflow steps by assigning a weight to each policy and constraint violation. To this end, we introduce a framework for associating costs with the violation of workflow policies and constraints and define the valued workflow Satisfiability Problem (Valued WSP), whose solution is an assignment of steps to users of minimum cost. We establish the computational complexity of Valued WSP with user-independent constraints and show that it is fixed-parameter tractable. We then describe an algorithm for solving Valued WSP with user-independent constraints and evaluate its performance, comparing it to that of an off-the-shelf mixed integer programming package.
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valued workflow Satisfiability Problem
arXiv: Data Structures and Algorithms, 2015Co-Authors: Jason Crampton, Gregory Gutin, Daniel KarapetyanAbstract:A workflow is a collection of steps that must be executed in some specific order to achieve an objective. A computerised workflow management system may enforce authorisation policies and constraints, thereby restricting which users can perform particular steps in a workflow. The existence of policies and constraints may mean that a workflow is unsatisfiable, in the sense that it is impossible to find an authorised user for each step in the workflow and satisfy all constraints. In this paper, we consider the Problem of finding the "least bad" assignment of users to workflow steps by assigning a weight to each policy and constraint violation. To this end, we introduce a framework for associating costs with the violation of workflow policies and constraints and define the \emph{valued workflow Satisfiability Problem} (Valued WSP), whose solution is an assignment of steps to users of minimum cost. We establish the computational complexity of Valued WSP with user-independent constraints and show that it is fixed-parameter tractable. We then describe an algorithm for solving Valued WSP with user-independent constraints and evaluate its performance, comparing it to that of an off-the-shelf mixed integer programming package.
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engineering algorithms for workflow Satisfiability Problem with user independent constraints
International Workshop on Frontiers in Algorithmics, 2014Co-Authors: David Cohen, Gregory Gutin, Jason Crampton, Andrei Gagarin, Mark JonesAbstract:The workflow Satisfiability Problem (WSP) is a planning Problem. Certain sub-classes of this Problem have been shown to be fixed-parameter tractable. In this paper we develop an implementation of an algorithm for WSP that has been shown, in our previous paper, to be fixed-parameter for user-independent constraints. In a set of computational experiments, we compare our algorithm to an encoding of the WSP into a pseudo-Boolean SAT Problem solved by the well-known solver SAT4J. Our algorithm solves all instances of WSP generated in our experiments, unlike SAT4J, and it solves many instances faster than SAT4J. For lightly constrained instances, SAT4J usually outperforms our algorithm.
Gregory Gutin - One of the best experts on this subject based on the ideXlab platform.
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GC - The Workflow Satisfiability Problem with User-Independent Constraints
2019 First International Conference on Graph Computing (GC), 2019Co-Authors: Gregory GutinAbstract:The Workflow Satisfiability Problem (WSP) is a Problem of interest in access control of information security. In its simplest form is the Problem coincides with the Constraint Satisfiability Problem, where the number of variables is usually much smaller than the number of values. Wang and Li (2010) were the first to study the WSP as a Problem parameterized by the number of variables. The paper initiated very fruitful research surveyed by Cohen, Crampton, Gutin and Wahlstrom (2017). In this paper, we briefly overview some more recent WSP algorithmic developments.
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the bi objective workflow Satisfiability Problem and workflow resiliency
Journal of Computer Security, 2017Co-Authors: Jason Crampton, Gregory Gutin, Daniel Karapetyan, Remi WatrigantAbstract:A computerized workflow management system may enforce a security policy, specified in terms of authorized actions and constraints, thereby restricting which users can perform particular steps in a workflow. The existence of a security policy may mean that a workflow is unsatisfiable, in the sense that it is impossible to find a valid plan (an assignment of steps to authorized users such that all constraints are satisfied). Work in the literature focuses on the workflow Satisfiability Problem, a decision Problem that outputs a valid plan if the instance is satisfiable (and a negative result otherwise). In this paper, we introduce the Bi-Objective Workflow Satisfiability Problem (BO-WSP), which enables us to solve optimization Problems related to workflows and security policies. In particular, we are able to compute a “least bad” plan when some components of the security policy may be violated. In general, BO-WSP is intractable from both the classical and parameterized complexity point of view (where the parameter is the number of steps). We prove that computing a Pareto front for BO-WSP is fixed-parameter tractable (FPT) if we restrict our attention to user-independent constraints. This result has important practical consequences, since most constraints of practical interest in the literature are user-independent. Our proof is constructive and defines an algorithm, the implementation of which we describe and evaluate. We also present a second algorithm to compute a Pareto front which solves multiples instances of a related Problem using mixed integer programming (MIP). We compare the performance of both our algorithms on synthetic instances, and show that the FPT algorithm outperforms the MIP-based one by several orders of magnitude on most instances. Finally, we study the important question of workflow resiliency and prove new results establishing that known decision Problems are fixed-parameter tractable when restricted to user-independent constraints. We then propose a new way of modeling the availability of users and demonstrate that many questions related to resiliency in the context of this new model may be reduced to instances of BO-WSP.
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the bi objective workflow Satisfiability Problem and workflow resiliency
arXiv: Cryptography and Security, 2015Co-Authors: Jason Crampton, Gregory Gutin, Daniel Karapetyan, Remi WatrigantAbstract:A computerized workflow management system may enforce a security policy, specified in terms of authorized actions and constraints, thereby restricting which users can perform particular steps in a workflow. The existence of a security policy may mean it is impossible to find a valid plan (an assignment of steps to authorized users such that all constraints are satisfied). Work in the literature focuses on the workflow Satisfiability Problem, a \emph{decision} Problem that outputs a valid plan if the instance is satisfiable (and a negative result otherwise). In this paper, we introduce the \textsc{Bi-Objective Workflow Satisfiability Problem} (\BOWSP), which enables us to solve \emph{optimization} Problems related to workflows and security policies. In particular, we are able to compute a "least bad" plan when some components of the security policy may be violated. In general, \BOWSP is intractable from both the classical and parameterized complexity point of view. We prove there exists an fixed-parameter tractable (FPT) algorithm to compute a Pareto front for \BOWSP if we restrict our attention to user-independent constraints. We also present a second algorithm to compute a Pareto front which uses mixed integer programming (MIP). We compare the performance of both our algorithms on synthetic instances, and show that the FPT algorithm outperforms the MIP-based one by several orders of magnitude on most of the instances. Finally, we study the important question of workflow resiliency and prove new results establishing that known decision Problems are fixed-parameter tractable when restricted to user-independent constraints. We then propose a new way of modeling the availability of users and demonstrate that many questions related to resiliency in the context of this new model may be reduced to instances of \BOWSP.
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valued workflow Satisfiability Problem
Symposium on Access Control Models and Technologies, 2015Co-Authors: Jason Crampton, Gregory Gutin, Daniel KarapetyanAbstract:A workflow is a collection of steps that must be executed in some specific order to achieve an objective. A computerised workflow management system may enforce authorisation policies and constraints, thereby restricting which users can perform particular steps in a workflow. The existence of policies and constraints may mean that a workflow is unsatisfiable, in the sense that it is impossible to find an authorised user for each step in the workflow and satisfy all constraints. In this paper, we consider the Problem of finding the "least bad" assignment of users to workflow steps by assigning a weight to each policy and constraint violation. To this end, we introduce a framework for associating costs with the violation of workflow policies and constraints and define the valued workflow Satisfiability Problem (Valued WSP), whose solution is an assignment of steps to users of minimum cost. We establish the computational complexity of Valued WSP with user-independent constraints and show that it is fixed-parameter tractable. We then describe an algorithm for solving Valued WSP with user-independent constraints and evaluate its performance, comparing it to that of an off-the-shelf mixed integer programming package.
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valued workflow Satisfiability Problem
arXiv: Data Structures and Algorithms, 2015Co-Authors: Jason Crampton, Gregory Gutin, Daniel KarapetyanAbstract:A workflow is a collection of steps that must be executed in some specific order to achieve an objective. A computerised workflow management system may enforce authorisation policies and constraints, thereby restricting which users can perform particular steps in a workflow. The existence of policies and constraints may mean that a workflow is unsatisfiable, in the sense that it is impossible to find an authorised user for each step in the workflow and satisfy all constraints. In this paper, we consider the Problem of finding the "least bad" assignment of users to workflow steps by assigning a weight to each policy and constraint violation. To this end, we introduce a framework for associating costs with the violation of workflow policies and constraints and define the \emph{valued workflow Satisfiability Problem} (Valued WSP), whose solution is an assignment of steps to users of minimum cost. We establish the computational complexity of Valued WSP with user-independent constraints and show that it is fixed-parameter tractable. We then describe an algorithm for solving Valued WSP with user-independent constraints and evaluate its performance, comparing it to that of an off-the-shelf mixed integer programming package.
