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Dischargeable Obligations in the SCIFF Framework

Alberti Marco, Gavanelli Marco, Lamma Evelina, Riguzzi Fabrizio, Satoh Ken, Zese Riccardo

Fundamenta Informaticae

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2020

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Vol. 176, nr 3/4

321--348

EN

Abductive Logic Programming (ALP) has been proven very effective for formalizing societies of agents, commitments and norms, in particular by mapping the most common deontic operators (obligation, prohibition, permission) to abductive expectations. In our previous works, we have shown that ALP is a suitable framework for representing norms. Normative reasoning and query answering were accommodated by the same abductive proof procedure, named SCIFF. In this work, we introduce a defeasible flavour in this framework, in order to possibly discharge obligations in some scenarios. Abductive expectations can also be qualified as dischargeable, in the new, extended syntax. Both declarative and operational semantics are improved accordingly, and proof of soundness is given under syntax allowedness conditions. Moreover, the dischargement itself might be proved invalid, or incoherent with the rules, due to new knowledge provided later on. In such a case, a discharged expectation might be reinstated and hold again after some evidence is given. We extend the notion of dischargement to take into consideration also the reinstatement of expectations. The expressiveness and power of the extended framework, named SCIFFD, is shown by modeling and reasoning upon a fragment of the Japanese Civil Code. In particular, we consider a case study concerning manifestations of intention and their rescission (Section II of the Japanese Civil Code).

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Evaluating Compliance : From LTL to Abductive Logic Programming

Chesani F., Gavanelli M., Lamma E., Mello P., Montali M.

Fundamenta Informaticae

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2018

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Vol. 159, nr 1/2

35--63

EN

The compliance verification task amounts to establishing if the execution of a system, given in terms of observed happened events, does respect a given property. In the past both the frameworks of Temporal Logics and Logic Programming have been extensively exploited to assess compliance in different domains, such as normative multi-agent systems, business process management and service oriented computing. In this work we review the LTL and SCIFF frameworks in the light of compliance evaluation, and formally investigate the relationship between the two approaches. We define a notion of compliance within each approach, and then we show that an arbitrary LTL formula can be expressed in SCIFF, by providing a translation procedure from LTL to SCIFF which preserves compliance.

3

Compliance in Business Processes with Incomplete Information and Time Constraints : a General Framework based on Abductive Reasoning

Chesani F., Mello P., Montali M., Tessaris S., De Masellis R., Di Francescomarino C., Ghidini C.

Fundamenta Informaticae

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2018

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Vol. 161, nr 1/2

75--111

EN

The capability to store data about Business Process (BP) executions in so-called Event Logs has brought to the identification of a range of key reasoning services (consistency, compliance, runtime monitoring, prediction) for the analysis of process executions and process models. Tools for the provision of these services typically focus on one form of reasoning alone. Moreover, they are often very rigid in dealing with forms of incomplete information about the process execution. While this enables the development of ad hoc solutions, it also poses an obstacle for the adoption of reasoning-based solutions in the BP community. In this paper, we introduce the notion of Structured Processes with Observability and Time (SPOT models), able to support incompleteness (of traces and logs), and temporal constraints on the activity duration and between activities. Then, we exploit the power of abduction to provide a flexible, yet computationally effective framework able to reinterpret key reasoning services in terms of incompleteness and observability in a uniform way.