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See detailProving Regulatory Compliance: Business Processes, Logic, Complexity
Colombo Tosatto, Silvano UL

Doctoral thesis (2015)

The problem of proving regulatory compliance of a business process model is composed of two main elements. One of these elements is the business process model, which provides a formal compact description ... [more ▼]

The problem of proving regulatory compliance of a business process model is composed of two main elements. One of these elements is the business process model, which provides a formal compact description of the available executions capable of achieving a given business objective. The other element is the regulatory framework that the business process must follow, describing the compliance requirements given by the law or by a company’s own internal regulations. The problem consists of verifying whether a given business process model is compliant with the regulatory framework, which is carried out by verifying whether the executions of the model comply with the requirements of the regulatory framework. Solutions to prove the regulatory compliance of business processes have been already proposed in the past. Some solutions disregard the computational complexity aspect of the problem, while other solutions either solve a simplified version of the problem efficiently or provide approximate solutions for the general one. However, none of these solutions have formally studied the computational complexity of the problem of proving regulatory compliance. This thesis addresses that issue, showing in addition why efficient solutions of the general problem are not possible. In particular I study the computational complexity of a problem of proving regulatory compliance whose regulatory framework is defined using conditional obligations. The approach I adopt to represent the compliance requirement is semantically similar to some of the existing solutions proposed by other researchers, such as van der Aalst and many others, who adopts linear temporal logic over finite traces, or different variants of such temporal logic, to define the compliance requirements. More precisely, the approach used in the present thesis adopts propositional logic as base logic, and defines the semantics of the regulatory framework in a similar way as Process Compliance Logic introduced by Governatori and Rotolo. The study of the computational complexity of the problem is approached by dividing it in sub-classes and then combining their analysis to obtain the result for the target problem. The division is done according to three features of the regulatory framework. These features define whether the framework is composed of a single or a set of obligations, whether the obligations are conditional and whether violations can be compensated. These features can be omitted to identify simpler sub-classes of the problem. After having identified the different sub-classes of the problem, I study the computational complexity of some of these sub-classes and combine the results obtained to identify the computational complexity of the general problem tackled in the present thesis, where each of the three features identified are used to describe the compliance requirements. The results of the computational complexity analysis show that proving the existence of an execution of a business process compliant with the regulatory framework is an NP-complete problem. Differently proving that for all of the executions of a business process model, they are either compliant or not with the regulatory framework, is a coNP-complete problem. The results show that combining the two elements composing the problem of proving regulatory compliance, the process model and the regulatory framework, which are tractable when considered individually, leads to an intractable problem. In addition to the computational complexity results, the analysis provided in the thesis has also shown that tractable sub-classes of the problem, where the computational complexity is at most polynomial with respect to the size of the input, can be obtained by trivialising the expressivity of either one of the elements composing the problem. However the expressivity of these sub-classes is limited. Thus I identify a different tractable sub-class of the problem by weakening the expressivity of both elements composing the problem, but where each element is not trivialised as for the other sub-classes. Whether the sub-class identified can be considered expressive is arguable, however it represents a first step towards identifying a sub-class of the problem being both tractable and expressive, taking into account the limitation of employing propositional logic as base logic. [less ▲]

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See detailAlgorithms for tractable compliance problems
Colombo Tosatto, Silvano UL; Kelsen, Pierre UL; Ma, Qin UL et al

in Frontiers of Computer Science (2015), 9(1), 55-74

In general the problem of verifying whether a structured business process is compliant with a given set of regulations is NP-hard. The present paper focuses on identifying a tractable subset of this ... [more ▼]

In general the problem of verifying whether a structured business process is compliant with a given set of regulations is NP-hard. The present paper focuses on identifying a tractable subset of this problem, namely verifying whether a structured business process is compliant with a single global obligation. Global obligations are those whose validity spans for the entire execution of a business process. We identify two types of obligations: achievement and maintenance. In the present paper we firstly define an abstract framework capable to model the problem and secondly we define procedures and algorithms to deal with the compliance problem of checking the compliance of a structured business process with respect to a single global obligation. We show that the algorithms proposed in the paper run in polynomial time. [less ▲]

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See detailBusiness Process Regulatory Compliance is Hard
Colombo Tosatto, Silvano UL; Kelsen, Pierre UL; Governatori, Guido

in IEEE Transactions on Services Computing (2015), 8(6), 958-970

Verifying whether a business process is compliant with a regulatory framework is a difficult task. In the present paper we prove the hardness of the business process regulatory compliance problem by ... [more ▼]

Verifying whether a business process is compliant with a regulatory framework is a difficult task. In the present paper we prove the hardness of the business process regulatory compliance problem by taking into account a sub-problem of the general problem. This limited problem allows to verify only the compliance of structured processes with respect to a regulatory framework composed of a set of conditional obligations including a deadline. Experimental evidence from existing studies shows that compliance is a difficult task. In this paper, despite considering a sub-problem of the general problem, we provide some theoretical evidence of the difficulty of the task. In particular we show that the source of the complexity lies in the core language of verifying conditional obligations with a deadline. We prove that for this simplified case verifying partial compliance belongs to the class of NP-complete problems, and verifying full compliance belongs to the class of coNP-complete problems. Thus by proving the difficulty of a simplified compliance problem we prove that the general problem of verifying business process regulatory compliance is hard. [less ▲]

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See detailBridging Social Network Analysis and Judgment Aggregation
Colombo Tosatto, Silvano UL; Van Zee, Marc UL

in Social Informatics - 6th International Conference, SocInfo 2014, Barcelona, Spain, November 11-13, 2014. Proceedings (2014)

Judgment aggregation investigates the problem of how to aggregate several individuals’ judgments on some logically connected propositions into a consistent collective judgment. The majority of work in ... [more ▼]

Judgment aggregation investigates the problem of how to aggregate several individuals’ judgments on some logically connected propositions into a consistent collective judgment. The majority of work in judgment aggregation is devoted to studying impossibility results, but the relationship between the (social) dependencies that may exist be- tween voters and the outcome of the voting process is traditionally not studied. In this paper, we use techniques from social network analysis to characterize the relations between the individuals participating in a judgment aggregation problem by analysing the similarity between their judgments in terms of social networks. We obtain a correspondence between a voting rule in judgment aggregation and a centrality measure from social network analysis and we motivate our claims by an empirical analysis. We also show how large social networks can be simplified by grouping individuals with the same voting behavior. [less ▲]

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See detailDetecting Deontic Conflicts in Dynamic Settings
Colombo Tosatto, Silvano UL; Kelsen, Pierre UL; Governatori, Guido

in Cariani, Fabrizio; Grossi, Davide; Meheus, Joke (Eds.) et al Deontic Logic and Normative Systems 12th International Conference, DEON 2014, Ghent, Belgium, July 12-15, 2014. Proceedings (2014)

Regulations, through the use of obligations and permissions, are widely used in modern society to define acceptable behaviours. Thus it is indeed important that these regulations do not conflict with each ... [more ▼]

Regulations, through the use of obligations and permissions, are widely used in modern society to define acceptable behaviours. Thus it is indeed important that these regulations do not conflict with each other and contain contradicting obligations. In the present paper we focus on identifying conflicts between obligations in dynamic settings. We first show the need of an alternative semantics rather than the more classic modelled by standard deontic logic. Second we introduce a new semantics for the obligations capable of representing and reasoning about them in these dynamic settings, and lastly we use it to identify the necessary and sufficient conditions to identify conflicting obligations. [less ▲]

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See detailSocial Network Analysis for Judgment Aggregation
Colombo Tosatto, Silvano UL; Van Zee, Marc UL

in Proceedings of the 13th International Conference on Autonomous Agents and Multiagent Systems (2014)

The majority of work in judgment aggregation is devoted to the study of impossibility results. However the (social) dependencies that may exist between the voters has received less attention. In this ... [more ▼]

The majority of work in judgment aggregation is devoted to the study of impossibility results. However the (social) dependencies that may exist between the voters has received less attention. In this extended abstract we use the degree centrality measure from social network analysis and obtain a correspondence between the average voter rule and this measure, and show that approach can lead to more resolute outcomes in the voting process. [less ▲]

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See detailIntegrating Legal-URN and Eunomos: towards a comprehensive compliance management solution
Boella, Guido; Colombo Tosatto, Silvano UL; Ghavanati, Sepideh et al

in Proceedings of AI Approaches to the Complexity of Legal Systems (AICOL 2013) (2014)

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See detailCompliance in Resource-based Process Models
Colombo Tosatto, Silvano UL; Elrakaiby, Yehia UL; Ziafati, Pouyan UL

in Hindriks, Koen; de Weerdt, Mathijs; van Riemsdijk, Birna (Eds.) et al Proceedings of the 25th Belgium-Netherlands Artificial Intelligence Conference (2013, November)

Execution of business processes often requires resources, the use of which is usually subject to constraints. In this paper, we study the compliance of business processes with resource usage policies. To ... [more ▼]

Execution of business processes often requires resources, the use of which is usually subject to constraints. In this paper, we study the compliance of business processes with resource usage policies. To this end, we relate the execution of a business process to its resource requirements in terms of resources consumed, produced or blocked by tasks of the business process. Policies specifying constraints on resource usage are specified in the form of obligations and the verification of whether a business process complies with a given resource usage policy is formally studied. [less ▲]

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See detailTowards an Abstract Framework for Compliance
Colombo Tosatto, Silvano UL; Governatori, Guido; Kelsen, Pierre UL

in Bagheri, Ebrahim; Gasevic, Dragan; Halle, Sylvain (Eds.) et al Proceedings of the 17th IEEE International EDOC 2013 Conference Workshops, Vancouver, Canada, 9 September 2013. (2013, September 09)

The present paper aims at providing an abstract framework to define the regulatory compliance problem. In particular we show how the framework can be used to solve the problem of deciding whether a ... [more ▼]

The present paper aims at providing an abstract framework to define the regulatory compliance problem. In particular we show how the framework can be used to solve the problem of deciding whether a structured process is compliant with a single regulation, which is composed of a primary obligation and a chain of compensations. [less ▲]

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See detailAlgorithms for Basic Compliance Problems
Colombo Tosatto, Silvano UL; El Kharbili, Marwane UL; Governatori, Guido et al

in 2nd International Workshop on Engineering Safety and Security Systems, ESSS 2013. (2013, March)

The present paper focuses on the problems of verifying compliance for global achievement and maintenance obligations. We first introduce the elements needed to identify and study compliance to these two ... [more ▼]

The present paper focuses on the problems of verifying compliance for global achievement and maintenance obligations. We first introduce the elements needed to identify and study compliance to these two classes of obligations in processes. Additionally, we define procedures and algorithms to efficiently deal with the identified compliance problem. We finally show that both algorithms proposed in the paper belong to the complexity class P. [less ▲]

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See detailAbstract Normative Systems: Semantics and Proof Theory
Colombo Tosatto, Silvano UL; Boella, Guido; van der Torre, Leon UL et al

in PRINCIPLES OF KNOWLEDGE REPRESENTATION AND REASONING: PROCEEDINGS OF THE THIRTEENTH INTERNATIONAL CONFERENCE (2012)

In this paper we introduce an abstract theory of normative reasoning, whose central notion is the generation of obligations, permissions and institutional facts from conditional norms. We present various ... [more ▼]

In this paper we introduce an abstract theory of normative reasoning, whose central notion is the generation of obligations, permissions and institutional facts from conditional norms. We present various semantics and their proof systems. The theory can be used to classify and compare new candidates for standards of normative reasoning, and to explore more elaborate forms of normative reasoning than studied thus far. [less ▲]

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See detailLearning and Reasoning about Norms using Neural-Symbolic Systems
Perotti, Alan; Boella, Guido; Colombo Tosatto, Silvano UL et al

in International Conference on Autonomous Agents and Multiagent Systems, AAMAS 2012, Valencia, Spain, June 4-8, 2012 (2012)

In this paper we provide a neural-symbolic framework to model, reason about and learn norms in multi-agent systems. To this purpose, we define a fragment of Input/Output (I/O) logic that can be embedded ... [more ▼]

In this paper we provide a neural-symbolic framework to model, reason about and learn norms in multi-agent systems. To this purpose, we define a fragment of Input/Output (I/O) logic that can be embedded into a neural network. We extend d’Avila Garcez et al. Connectionist Inductive Learning and Logic Programming System (CILP) to translate an I/O logic theory into a Neural Network (NN) that can be trained further with examples: we call this new system Normative- CILP (N-CILP). We then present a new algorithm to handle priorities between rules in order to cope with normative issues like Contrary to Duty (CTD), Priorities, Exceptions and Permissions. We illustrate the applicability of the framework on a case study based on RoboCup rules: within this working example, we compare the learning capacity of a network built with N-CILP with a non symbolic neural net- work, we explore how the initial knowledge impacts on the overall performance, and we test the NN capacity of learn- ing norms, generalizing new Contrary to Duty rules from examples. [less ▲]

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See detailVisualizing Normative Systems: an Abstract Approach
Colombo Tosatto, Silvano UL; Boella, Guido; van der Torre, Leon UL et al

in Agotnes, Thomas; Broersen, Jan; Elgesem, Dag (Eds.) Deontic Logic in Computer Science - 11th International Conference, DEON 2012, Bergen, Norway, July 16-18, 2012. Proceedings (2012)

Abstract normative systems allow to reason with norms even when their content is not detailed. In this paper, we propose a our preliminary results to visualize abstract normative systems, in such a way ... [more ▼]

Abstract normative systems allow to reason with norms even when their content is not detailed. In this paper, we propose a our preliminary results to visualize abstract normative systems, in such a way that we are able to reason with institutional facts, obligations and permissions. Moreover, we detect meaningful patterns emerging from the proposed visualization, and we show how these patterns can be used to define commonly used reusable solutions. [less ▲]

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See detailContrary-To-Duties in Games
Turrini, Paolo UL; Parent, Xavier UL; van der Torre, Leon UL et al

in Logic Programs, Norms and Action: Essays in Honor of Marek J. Sergot on the Occasion of His 60th Birthday (Lecture Notes in Computer Science / Lecture Notes in Artificial Intelligence) (2012)

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See detailNeural Symbolic Architecture for Normative Agents
Boella, Guido; Colombo Tosatto, Silvano UL; d'Avila Garcez, Artur et al

in In Proceedings of The Seventh International Conference on Autonomous Agents and Multiagent Systems (AAMAS 2011). May, 2011 (2011)

In this paper we propose a neural-symbolic architecture to represent and reason with norms in multi-agent systems. On the one hand, the architecture contains a symbolic knowledge base to represent norms ... [more ▼]

In this paper we propose a neural-symbolic architecture to represent and reason with norms in multi-agent systems. On the one hand, the architecture contains a symbolic knowledge base to represent norms and on the other hand it contains a neural network to reason with norms. The interaction between the symbolic knowledge and the neural network is used to learn norms. We describe how to handle normative reasoning issues like contrary to duties, dilemmas and exceptions by using a priority-based ordering between the norms in a neural-symbolic architecture. [less ▲]

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See detailEmbedding Normative Reasoning into Neural Symbolic Systems
Boella, Guido; Colombo Tosatto, Silvano UL; d'Avila Garcez, Artur et al

in Proceedings of the Seventh International Workshop on Neural-Symbolic Learning and Reasoning (2011)

Normative systems are dynamic systems because their rules can change over time. Considering this problem, we propose a neural- symbolic approach to provide agents the instru- ments to reason about and ... [more ▼]

Normative systems are dynamic systems because their rules can change over time. Considering this problem, we propose a neural- symbolic approach to provide agents the instru- ments to reason about and learn norms in a dynamic environment. We propose a variant of d’Avila Garcez et al. Con- nectionist Inductive Learning and Logic Program- ming(CILP) System to embed Input/Output logic normative rules into a feed-forward neural network. The resulting system called Normative-CILP(N- CILP) shows how neural networks can cope with some of the underpinnings of normative reasoning: permissions , dilemmas , exceptions and contrary to duty problems. We have applied our approach in a simplified RoboCup environment, using the N-CILP simula- tor that we have developed. In the concluding part of the paper, we provide some of the results ob- tained in the experiments [less ▲]

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See detailOn the Relationship between I-O Logic and Connectionism
Boella, Guido; Colombo Tosatto, Silvano UL; d'Avila Garcez, Artur S. et al

in In Proceedings of the 14th International Workshop on Non-Monotonic Reasoning (NMR'10), Toronto, Canada, May 2010 (2010)

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