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2020
Book
Open Access
Proceedings of the 4th International Workshop on MIning and REasoning with Legal texts (MIREL 2019)
Casini G, Di Caro L, Governatori G, Leone V, Markovich R
Proceedings of the 4th International Workshop on MIning and REasoning with Legal texts (MIREL 2019), co-located with the 32nd International Conference on Legal Knowledge and Information Systems (JURIX 2019).Source: CEUR WORKSHOP PROCEEDINGS
Casini G, Di Caro L, Governatori G, Leone V, Markovich R
Proceedings of the 4th International Workshop on MIning and REasoning with Legal texts (MIREL 2019), co-located with the 32nd International Conference on Legal Knowledge and Information Systems (JURIX 2019).Source: CEUR WORKSHOP PROCEEDINGS
See at:
ceur-ws.org 
| CNR IRIS | ISTI Repository | CNR IRIS 
| CNR IRIS
2020
Conference article
Open Access
BKLM - An expressive logic for defeasible reasoning
Patersonjones G, Casini G, Meyer T
Propositional KLM-style defeasible reasoning involves a core propositional logic capable of expressing defeasible (or conditional) implications. The semantics for this logic is based on Kripke-like structures known as ranked interpretations. KLM-style defeasible entailment is referred to as rational whenever the defeasible entailment relation under consideration generates a set of defeasible implications all satisfying a set of rationality postulates known as the KLM postulates. In a recent paper Booth et al. proposed PTL, a logic that is more expressive than the core KLM logic. They proved an impossibility result, showing that defeasible entailment for PTL fails to satisfy a set of rationality postulates similar in spirit to the KLM postulates. Their interpretation of the impossibility result is that defeasible entailment for PTL need not be unique. In this paper we continue the line of research in which the expressivity of the core KLM logic is extended. We present the logic Boolean KLM (BKLM) in which we allow for disjunctions, conjunctions, and negations, but not nesting, of defeasible implications. Our contribution is twofold. Firstly, we show (perhaps surprisingly) that BKLM is more expressive than PTL. Our proof is based on the fact that BKLM can characterise all single ranked interpretations, whereas PTL cannot. Secondly, given that the PTL impossibility result also applies to BKLM, we adapt the different forms of PTL entailment proposed by Booth et al. to apply to BKLM.
Patersonjones G, Casini G, Meyer T
Propositional KLM-style defeasible reasoning involves a core propositional logic capable of expressing defeasible (or conditional) implications. The semantics for this logic is based on Kripke-like structures known as ranked interpretations. KLM-style defeasible entailment is referred to as rational whenever the defeasible entailment relation under consideration generates a set of defeasible implications all satisfying a set of rationality postulates known as the KLM postulates. In a recent paper Booth et al. proposed PTL, a logic that is more expressive than the core KLM logic. They proved an impossibility result, showing that defeasible entailment for PTL fails to satisfy a set of rationality postulates similar in spirit to the KLM postulates. Their interpretation of the impossibility result is that defeasible entailment for PTL need not be unique. In this paper we continue the line of research in which the expressivity of the core KLM logic is extended. We present the logic Boolean KLM (BKLM) in which we allow for disjunctions, conjunctions, and negations, but not nesting, of defeasible implications. Our contribution is twofold. Firstly, we show (perhaps surprisingly) that BKLM is more expressive than PTL. Our proof is based on the fact that BKLM can characterise all single ranked interpretations, whereas PTL cannot. Secondly, given that the PTL impossibility result also applies to BKLM, we adapt the different forms of PTL entailment proposed by Booth et al. to apply to BKLM.
See at:
CNR IRIS | nmr2020.dc.uba.ar | ISTI Repository | CNR IRIS
2020
Conference article
Open Access
Rational defeasible belief change
Casini G, Meyer T, Varzinczak I
We present a formal framework for modelling belief change within a nonmonotonic reasoning system. Belief change and non-monotonic reasoning are two areas that are formally closely related, with recent attention being paid towards the analysis of belief change within a non-monotonic environment. In this paper we consider the classical AGM belief change operators, contraction and revision, applied to a defeasible setting in the style of Kraus, Lehmann, and Magidor. The investigation leads us to the consideration of the problem of iterated change, generalising the classical work of Darwiche and Pearl. We characterise a family of operators for iterated revision, followed by an analogous characterisation of operators for iterated contraction. We start considering belief change operators aimed at preserving logical consistency, and then characterise analogous operators aimed at the preservation of coherence--an important notion within the field of logic-based ontologies.Source: PROCEEDINGS INTERNATIONAL CONFERENCE ON PRINCIPLES OF KNOWLEDGE REPRESENTATION AND REASONING, pp. 213-222. Online conference, 12-18/09/2020
DOI: 10.24963/kr.2020/22
Metrics:
Casini G, Meyer T, Varzinczak I
We present a formal framework for modelling belief change within a nonmonotonic reasoning system. Belief change and non-monotonic reasoning are two areas that are formally closely related, with recent attention being paid towards the analysis of belief change within a non-monotonic environment. In this paper we consider the classical AGM belief change operators, contraction and revision, applied to a defeasible setting in the style of Kraus, Lehmann, and Magidor. The investigation leads us to the consideration of the problem of iterated change, generalising the classical work of Darwiche and Pearl. We characterise a family of operators for iterated revision, followed by an analogous characterisation of operators for iterated contraction. We start considering belief change operators aimed at preserving logical consistency, and then characterise analogous operators aimed at the preservation of coherence--an important notion within the field of logic-based ontologies.Source: PROCEEDINGS INTERNATIONAL CONFERENCE ON PRINCIPLES OF KNOWLEDGE REPRESENTATION AND REASONING, pp. 213-222. Online conference, 12-18/09/2020
DOI: 10.24963/kr.2020/22
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CNR IRIS | library.confdna.com | ISTI Repository | doi.org | CNR IRIS | www.scopus.com
2020
Journal article
Open Access
Principles of KLM-style Defeasible Description Logics
Britz K, Casini G, Meyer T, Moodley K, Sattler U, Varzinczak I
The past 25 years have seen many attempts to introduce defeasible-reasoning capabilities into a description logic setting. Many, if not most, of these attempts are based on preferential extensions of description logics, with a significant number of these, in turn, following the so-called KLM approach to defeasible reasoning initially advocated for propositional logic by Kraus, Lehmann, and Magidor. Each of these attempts has its own aim of investigating particular constructions and variants of the (KLM-style) preferential approach. Here our aim is to provide a comprehensive study of the formal foundations of preferential defeasible reasoning for description logics in the KLM tradition.We start by investigating a notion of defeasible subsumption in the spirit of defeasible conditionals as studied by Kraus, Lehmann, and Magidor in the propositional case. In particular, we consider a natural and intuitive semantics for defeasible subsumption, and we investigate KLM-style syntactic properties for both preferential and rational subsumption. Our contribution includes two representation results linking our semantic constructions to the set of preferential and rational properties considered. Besides showing that our semantics is appropriate, these results pave the way for more effective decision procedures for defeasible reasoning in description logics. Indeed, we also analyse the problem of non-monotonic reasoning in description logics at the level of entailment and present an algorithm for the computation of rational closure of a defeasible knowledge base. Importantly, our algorithm relies completely on classical entailment and shows that the computational complexity of reasoning over defeasible knowledge bases is no worse than that of reasoning in the underlying classical DL ALC.Source: ACM TRANSACTIONS ON COMPUTATIONAL LOGIC, vol. 22 (issue 1), pp. 1-46
DOI: 10.1145/3420258
Metrics:
Britz K, Casini G, Meyer T, Moodley K, Sattler U, Varzinczak I
The past 25 years have seen many attempts to introduce defeasible-reasoning capabilities into a description logic setting. Many, if not most, of these attempts are based on preferential extensions of description logics, with a significant number of these, in turn, following the so-called KLM approach to defeasible reasoning initially advocated for propositional logic by Kraus, Lehmann, and Magidor. Each of these attempts has its own aim of investigating particular constructions and variants of the (KLM-style) preferential approach. Here our aim is to provide a comprehensive study of the formal foundations of preferential defeasible reasoning for description logics in the KLM tradition.We start by investigating a notion of defeasible subsumption in the spirit of defeasible conditionals as studied by Kraus, Lehmann, and Magidor in the propositional case. In particular, we consider a natural and intuitive semantics for defeasible subsumption, and we investigate KLM-style syntactic properties for both preferential and rational subsumption. Our contribution includes two representation results linking our semantic constructions to the set of preferential and rational properties considered. Besides showing that our semantics is appropriate, these results pave the way for more effective decision procedures for defeasible reasoning in description logics. Indeed, we also analyse the problem of non-monotonic reasoning in description logics at the level of entailment and present an algorithm for the computation of rational closure of a defeasible knowledge base. Importantly, our algorithm relies completely on classical entailment and shows that the computational complexity of reasoning over defeasible knowledge bases is no worse than that of reasoning in the underlying classical DL ALC.Source: ACM TRANSACTIONS ON COMPUTATIONAL LOGIC, vol. 22 (issue 1), pp. 1-46
DOI: 10.1145/3420258
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dl.acm.org | CNR IRIS | NARCIS | ACM Transactions on Computational Logic | CNR IRIS | CNR IRIS
2021
Conference article
Open Access
Contextual conditional reasoning
Casini G, Meyer T, Varzinczak I
We extend the expressivity of classical conditional reasoning by introducing context as a new parameter. The enriched conditional logic generalises the defeasible conditional setting in the style of Kraus, Lehmann, and Magidor, and allows for a refined semantics that is able to distinguish, for example, between expectations and counterfactuals. In this paper we introduce the language for the enriched logic and define an appropriate semantic framework for it. We analyse which properties generally associated with conditional reasoning are still satisfied by the new semantic framework, provide a suitable representation result, and define an entailment relation based on Lehmann and Magidor's generally-accepted notion of Rational Closure.Source: PROCEEDINGS OF THE ... AAAI CONFERENCE ON ARTIFICIAL INTELLIGENCE, pp. 6254-6261. Online Conference, 2-9/2/2021
Casini G, Meyer T, Varzinczak I
We extend the expressivity of classical conditional reasoning by introducing context as a new parameter. The enriched conditional logic generalises the defeasible conditional setting in the style of Kraus, Lehmann, and Magidor, and allows for a refined semantics that is able to distinguish, for example, between expectations and counterfactuals. In this paper we introduce the language for the enriched logic and define an appropriate semantic framework for it. We analyse which properties generally associated with conditional reasoning are still satisfied by the new semantic framework, provide a suitable representation result, and define an entailment relation based on Lehmann and Magidor's generally-accepted notion of Rational Closure.Source: PROCEEDINGS OF THE ... AAAI CONFERENCE ON ARTIFICIAL INTELLIGENCE, pp. 6254-6261. Online Conference, 2-9/2/2021
See at:
CNR IRIS | ojs.aaai.org | ISTI Repository | CNR IRIS
2021
Other
Open Access
Situated conditional reasoning
Casini G, Meyer T, Varzinczak I
Conditionals are useful for modelling, but aren't always sufficiently expressive for capturing information accurately. In this paper we make the case for a form of conditional that is situation-based. These conditionals are more expressive than classical conditionals, are general enough to be used in several application domains, and are able to distinguish, for example, between expectations and counterfactuals. Formally, they are shown to generalise the conditional setting in the style of Kraus, Lehmann, and Magidor. We show that situation-based conditionals can be described in terms of a set of rationality postulates. We then propose an intuitive semantics for these conditionals, and present a representation result which shows that our semantic construction corresponds exactly to the description in terms of postulates. With the semantics in place, we proceed to define a form of entailment for situated conditional knowledge bases, which we refer to as minimal closure. It is reminiscent of and, indeed, inspired by, the version of entailment for propositional conditional knowledge bases known as rational closure. Finally, we proceed to show that it is possible to reduce the computation of minimal closure to a series of propositional entailment and satisfiability checks. While this is also the case for rational closure, it is somewhat surprising that the result carries over to minimal closure.DOI: 10.32079/isti-tr-2021/009
Metrics:
Casini G, Meyer T, Varzinczak I
Conditionals are useful for modelling, but aren't always sufficiently expressive for capturing information accurately. In this paper we make the case for a form of conditional that is situation-based. These conditionals are more expressive than classical conditionals, are general enough to be used in several application domains, and are able to distinguish, for example, between expectations and counterfactuals. Formally, they are shown to generalise the conditional setting in the style of Kraus, Lehmann, and Magidor. We show that situation-based conditionals can be described in terms of a set of rationality postulates. We then propose an intuitive semantics for these conditionals, and present a representation result which shows that our semantic construction corresponds exactly to the description in terms of postulates. With the semantics in place, we proceed to define a form of entailment for situated conditional knowledge bases, which we refer to as minimal closure. It is reminiscent of and, indeed, inspired by, the version of entailment for propositional conditional knowledge bases known as rational closure. Finally, we proceed to show that it is possible to reduce the computation of minimal closure to a series of propositional entailment and satisfiability checks. While this is also the case for rational closure, it is somewhat surprising that the result carries over to minimal closure.DOI: 10.32079/isti-tr-2021/009
Metrics:
See at:
CNR IRIS | ISTI Repository | CNR IRIS
2021
Conference article
Open Access
KLM-style defeasibility for restricted first-order logic
Casini G, Meyer T, Patersonjones G
We extend the KLM approach to defeasible reasoning to be applicable to a restricted version of first-order logic. We describe defeasibility for this logic using a set of rationality postulates, provide an appropriate semantics for it, and present a representation result that characterises the semantic description of defeasibility in terms of the rationality postulates. Based on this theoretical core, we then propose a version of defeasible entailment that is inspired by Rational Closure as it is defined for defeasible propositional logic and defeasible description logics. We show that this form of defeasible entailment is rational in the sense that it adheres to our rationality postulates. The work in this paper is the first step towards our ultimate goal of introducing KLM-style defeasible reasoning into the family of Datalog+/- ontology languages.
Casini G, Meyer T, Patersonjones G
We extend the KLM approach to defeasible reasoning to be applicable to a restricted version of first-order logic. We describe defeasibility for this logic using a set of rationality postulates, provide an appropriate semantics for it, and present a representation result that characterises the semantic description of defeasibility in terms of the rationality postulates. Based on this theoretical core, we then propose a version of defeasible entailment that is inspired by Rational Closure as it is defined for defeasible propositional logic and defeasible description logics. We show that this form of defeasible entailment is rational in the sense that it adheres to our rationality postulates. The work in this paper is the first step towards our ultimate goal of introducing KLM-style defeasible reasoning into the family of Datalog+/- ontology languages.
See at:
drive.google.com | CNR IRIS | ISTI Repository | CNR IRIS
2021
Book
Open Access
Guest editorial Special Issue: Mining and Reasoning with Legal Texts
Robaldo L, Van Der Torre L, Casini G, Villata S
Journal of Applied Logics - IfCoLog Journal, vol. 8 (4). Special Issue: Mining and Reasoning with Legal Texts
Robaldo L, Van Der Torre L, Casini G, Villata S
Journal of Applied Logics - IfCoLog Journal, vol. 8 (4). Special Issue: Mining and Reasoning with Legal Texts
See at:
collegepublications.co.uk | CNR IRIS | ISTI Repository | CNR IRIS
2020
Conference article
Open Access
A boolean extension of KLM-Style conditional reasoning
Patersonjones G, Casini G, Meyer T
Propositional KLM-style defeasible reasoning involves extending propositional logic with a new logical connective that can express defeasible (or conditional) implications, with semantics given by ordered structures known as ranked interpretations. KLM-style defeasible entailment is referred to as rational whenever the defeasible entailment relation under consideration generates a set of defeasible implications all satisfying a set of rationality postulates known as the KLM postulates. In a recent paper Booth et al. proposed PTL, a logic that is more expressive than the core KLM logic. They proved an impossibility result, showing that defeasible entailment for PTL fails to satisfy a set of rationality postulates similar in spirit to the KLM postulates. Their interpretation of the impossibility result is that defeasible entailment for PTL need not be unique. In this paper we continue the line of research in which the expressivity of the core KLM logic is extended. We present the logic Boolean KLM (BKLM) in which we allow for disjunctions, conjunctions, and negations, but not nesting, of defeasible implications. Our contribution is twofold. Firstly, we show (perhaps surprisingly) that BKLMis more expressive than PTL. Our proof is based on the fact that BKLM can characterise all single ranked interpretations, whereas PTL cannot. Secondly, given that the PTL impossibility result also applies to BKLM, we adapt the dierent forms of PTL entailment proposed by Booth et al. to apply to BKLM.DOI: 10.1007/978-3-030-66151-9_15
Project(s): TAILOR
Metrics:
Patersonjones G, Casini G, Meyer T
Propositional KLM-style defeasible reasoning involves extending propositional logic with a new logical connective that can express defeasible (or conditional) implications, with semantics given by ordered structures known as ranked interpretations. KLM-style defeasible entailment is referred to as rational whenever the defeasible entailment relation under consideration generates a set of defeasible implications all satisfying a set of rationality postulates known as the KLM postulates. In a recent paper Booth et al. proposed PTL, a logic that is more expressive than the core KLM logic. They proved an impossibility result, showing that defeasible entailment for PTL fails to satisfy a set of rationality postulates similar in spirit to the KLM postulates. Their interpretation of the impossibility result is that defeasible entailment for PTL need not be unique. In this paper we continue the line of research in which the expressivity of the core KLM logic is extended. We present the logic Boolean KLM (BKLM) in which we allow for disjunctions, conjunctions, and negations, but not nesting, of defeasible implications. Our contribution is twofold. Firstly, we show (perhaps surprisingly) that BKLMis more expressive than PTL. Our proof is based on the fact that BKLM can characterise all single ranked interpretations, whereas PTL cannot. Secondly, given that the PTL impossibility result also applies to BKLM, we adapt the dierent forms of PTL entailment proposed by Booth et al. to apply to BKLM.DOI: 10.1007/978-3-030-66151-9_15
Project(s): TAILOR
Metrics:
See at:
CNR IRIS | link.springer.com | ISTI Repository | OpenAIRE | CNR IRIS | CNR IRIS
2022
Conference article
Open Access
Situated conditionals - A brief introduction
Casini G, Meyer T, Varzinczak I
We extend the expressivity of classical conditional reasoning by introducing situation as a new parameter. The enriched conditional logic generalises the defeasible conditional setting in the style of Kraus, Lehmann, and Magidor, and allows for a refined semantics that is able to distinguish, for example, between expectations and counterfactuals. We introduce the language for the enriched logic and define an appropriate semantic framework for it. We analyse which properties generally associated with conditional reasoning are still satisfied by the new semantic framework, provide a suitable representation result, and define an entailment relation based on Lehmann and Magidor's generally-accepted notion of RationalClosure.Source: CEUR WORKSHOP PROCEEDINGS, pp. 151-154. Haifa, Israel, 07-09/08/2022
Project(s): TAILOR
Casini G, Meyer T, Varzinczak I
We extend the expressivity of classical conditional reasoning by introducing situation as a new parameter. The enriched conditional logic generalises the defeasible conditional setting in the style of Kraus, Lehmann, and Magidor, and allows for a refined semantics that is able to distinguish, for example, between expectations and counterfactuals. We introduce the language for the enriched logic and define an appropriate semantic framework for it. We analyse which properties generally associated with conditional reasoning are still satisfied by the new semantic framework, provide a suitable representation result, and define an entailment relation based on Lehmann and Magidor's generally-accepted notion of RationalClosure.Source: CEUR WORKSHOP PROCEEDINGS, pp. 151-154. Haifa, Israel, 07-09/08/2022
Project(s): TAILOR
See at:
ceur-ws.org | CNR IRIS | ISTI Repository | CNR IRIS
2022
Book
Open Access
Proceedings of the 20th International Workshop on Non-Monotonic Reasoning (NMR 2022)
Arieli O, Casini G, Giordano L
Proceedings of the 20th International Workshop on Non-Monotonic Reasoning (NMR2022)Source: CEUR WORKSHOP PROCEEDINGS
Arieli O, Casini G, Giordano L
Proceedings of the 20th International Workshop on Non-Monotonic Reasoning (NMR2022)Source: CEUR WORKSHOP PROCEEDINGS
See at:
ceur-ws.org | CNR IRIS | ISTI Repository | CNR IRIS
2023
Journal article
Open Access
Situated conditional reasoning
Casini G, Meyer T, Varzinczak I
Conditionals are useful for modelling many forms of everyday human reasoning but are not always sufficiently expressive to represent the information we want to reason about. In this paper, we make a case for a form of situated conditional. By 'situated', we mean that there is a context, based on an agent's beliefs and expectations, that works as background information in evaluating a conditional, and we allow such a context to vary. These conditionals are able to distinguish, for example, between expectations and counterfactuals. Formally, they are shown to generalise the conditional setting in the style of Kraus, Lehmann, and Magidor. We show that situated conditionals can be described in terms of a set of rationality postulates. We then propose an intuitive semantics for these conditionals and present a representation result which shows that our semantic construction corresponds exactly to the description in terms of postulates. With the semantics in place, we define a form of entailment for situated conditional knowledge bases, which we refer to as minimal closure. Finally, we proceed to show that it is possible to reduce the computation of minimal closure to a series of propositional entailment and satisfiability checks. While this is also the case for rational closure, it is somewhat surprising that the result carries over to minimal closure.Source: ARTIFICIAL INTELLIGENCE, vol. 319
DOI: 10.1016/j.artint.2023.103917
DOI: 10.48550/arxiv.2109.01552
Project(s): TAILOR
Metrics:
Casini G, Meyer T, Varzinczak I
Conditionals are useful for modelling many forms of everyday human reasoning but are not always sufficiently expressive to represent the information we want to reason about. In this paper, we make a case for a form of situated conditional. By 'situated', we mean that there is a context, based on an agent's beliefs and expectations, that works as background information in evaluating a conditional, and we allow such a context to vary. These conditionals are able to distinguish, for example, between expectations and counterfactuals. Formally, they are shown to generalise the conditional setting in the style of Kraus, Lehmann, and Magidor. We show that situated conditionals can be described in terms of a set of rationality postulates. We then propose an intuitive semantics for these conditionals and present a representation result which shows that our semantic construction corresponds exactly to the description in terms of postulates. With the semantics in place, we define a form of entailment for situated conditional knowledge bases, which we refer to as minimal closure. Finally, we proceed to show that it is possible to reduce the computation of minimal closure to a series of propositional entailment and satisfiability checks. While this is also the case for rational closure, it is somewhat surprising that the result carries over to minimal closure.Source: ARTIFICIAL INTELLIGENCE, vol. 319
DOI: 10.1016/j.artint.2023.103917
DOI: 10.48550/arxiv.2109.01552
Project(s): TAILOR
Metrics:
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arXiv.org e-Print Archive | CNR IRIS | ISTI Repository | www.sciencedirect.com | Artificial Intelligence | doi.org | CNR IRIS | CNR IRIS
2022
Book
Open Access
Handbook of legal AI
Casini G, Robaldo L, Van Der Torre L, Villata S
The Handbook of Legal AI presents a comprehensive overview of the state-of-the-art and trends in the research field of legal AI. The handbook provides a solid introduction to the essentials of the field for newcomers and a selection of advanced issues as a base for future research directions. As the law gets more complex, conflicting, and ever-changing, more advanced methods, most of them come from the Artifi cial Intelligence (AI) field, are required for analyzing, representing and reasoning on legal knowledge. The discipline that tackles these challenges is now known as "Legal Artificial Intelligence". Legal AI is experiencing, in particular, in the latest years growth in activity, also at the industrial level, touching a variety of issues which go from the analysis of the textual content of the law, to reasoning about legal interpretation to ethical issues of AI applications in the legal domain (e.g., the artificial judge). This Handbook presents a collection of chapters which evolves around three main topics, namely norm mining (i.e., how to automatically identify, extract, classify and interlink norms from text), reasoning about norms and regulations (i.e., how to derive new legal knowledge from the existing legal knowledge bases in such a way to address automatic legal decision making), and norm enforcement and compliance (i.e., how to check and ensure the compliance of the systems' requirements with the regulation).Project(s): TAILOR
Casini G, Robaldo L, Van Der Torre L, Villata S
The Handbook of Legal AI presents a comprehensive overview of the state-of-the-art and trends in the research field of legal AI. The handbook provides a solid introduction to the essentials of the field for newcomers and a selection of advanced issues as a base for future research directions. As the law gets more complex, conflicting, and ever-changing, more advanced methods, most of them come from the Artifi cial Intelligence (AI) field, are required for analyzing, representing and reasoning on legal knowledge. The discipline that tackles these challenges is now known as "Legal Artificial Intelligence". Legal AI is experiencing, in particular, in the latest years growth in activity, also at the industrial level, touching a variety of issues which go from the analysis of the textual content of the law, to reasoning about legal interpretation to ethical issues of AI applications in the legal domain (e.g., the artificial judge). This Handbook presents a collection of chapters which evolves around three main topics, namely norm mining (i.e., how to automatically identify, extract, classify and interlink norms from text), reasoning about norms and regulations (i.e., how to derive new legal knowledge from the existing legal knowledge bases in such a way to address automatic legal decision making), and norm enforcement and compliance (i.e., how to check and ensure the compliance of the systems' requirements with the regulation).Project(s): TAILOR
See at:
CNR IRIS | www.collegepublications.co.uk | CNR IRIS
2022
Journal article
Open Access
Normative change: an AGM approach
Maranhàƒo Jsa, Casini G, Van Der Torre L, Pigozzi G
Studying normative change has practical and theoretical interests. Changing legal rules poses interpretation problems to determine the content of legal rules. The question of interpretation is tightly linked to those of determining the validity and the ability to produce effects of legal rules. Different formal models of normative change seem better suited to capture these dimensions: the dimension of validity appears to be better captured by the AGM approach, whereas syntactic methods are better suited to model how rules' effects are blocked or enabled. Historically, the AGM approach of belief revision (on which we focus in this chapter) was the first formal model of normative change. We provide a survey on the AGM approach along with the main criticisms made to it. We then turn to a formal analysis of normative change that combines AGM theory and input/output logic, allowing for a clear distinction between norms and obligations. Our approach addresses some of the difficulties of normative change, like the combination of constitutive and regulative rules (and the normative conflicts that may arise from such a combination), the revision and contraction of normative systems, as well as the contraction of normative systems that combine sets of constitutive and regulative rules. We end our chapter by highlighting and discussing some challenges and open problems of normative change in the AGM approach.Source: JOURNAL OF APPLIED LOGICS, vol. 9 (issue 4), pp. 825-889
Project(s): TAILOR
Maranhàƒo Jsa, Casini G, Van Der Torre L, Pigozzi G
Studying normative change has practical and theoretical interests. Changing legal rules poses interpretation problems to determine the content of legal rules. The question of interpretation is tightly linked to those of determining the validity and the ability to produce effects of legal rules. Different formal models of normative change seem better suited to capture these dimensions: the dimension of validity appears to be better captured by the AGM approach, whereas syntactic methods are better suited to model how rules' effects are blocked or enabled. Historically, the AGM approach of belief revision (on which we focus in this chapter) was the first formal model of normative change. We provide a survey on the AGM approach along with the main criticisms made to it. We then turn to a formal analysis of normative change that combines AGM theory and input/output logic, allowing for a clear distinction between norms and obligations. Our approach addresses some of the difficulties of normative change, like the combination of constitutive and regulative rules (and the normative conflicts that may arise from such a combination), the revision and contraction of normative systems, as well as the contraction of normative systems that combine sets of constitutive and regulative rules. We end our chapter by highlighting and discussing some challenges and open problems of normative change in the AGM approach.Source: JOURNAL OF APPLIED LOGICS, vol. 9 (issue 4), pp. 825-889
Project(s): TAILOR
See at:
CNR IRIS | www.collegepublications.co.uk | CNR IRIS
2022
Conference article
Open Access
KLM-style defeasibility for restricted first-order logic
Casini G, Meyer T, Patersonjones G, Varzinczak I
In this paper, we extend the KLM approach to defeasible reasoning beyond the propositional setting. We do so by making it applicable to a restricted version of first-order logic. We describe defeasibility for this logic using a set of rationality postulates, provide a suitable and intuitive semantics for it, and present a representation result characterising the semantic description of defeasibility in terms of our postulates. An advantage of our semantics is that it is sufficiently general to be applicable to other restricted versions of first-order logic as well. Based on this theoretical core, we then propose a version of defeasible entailment that is inspired by the well-known notion of Rational Closure as it is defined for defeasible propositional logic and defeasible description logics. We show that this form of defeasible entailment is rational in the sense that it adheres to the full set of rationality postulates.DOI: 10.1007/978-3-031-21541-4_6
Project(s): TAILOR
Metrics:
Casini G, Meyer T, Patersonjones G, Varzinczak I
In this paper, we extend the KLM approach to defeasible reasoning beyond the propositional setting. We do so by making it applicable to a restricted version of first-order logic. We describe defeasibility for this logic using a set of rationality postulates, provide a suitable and intuitive semantics for it, and present a representation result characterising the semantic description of defeasibility in terms of our postulates. An advantage of our semantics is that it is sufficiently general to be applicable to other restricted versions of first-order logic as well. Based on this theoretical core, we then propose a version of defeasible entailment that is inspired by the well-known notion of Rational Closure as it is defined for defeasible propositional logic and defeasible description logics. We show that this form of defeasible entailment is rational in the sense that it adheres to the full set of rationality postulates.DOI: 10.1007/978-3-031-21541-4_6
Project(s): TAILOR
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2023
Book
Open Access
Preface for the first Workshop on AI-driven heterogeneous data management: Completing, merging, handling inconsistencies and query-answering (ENIGMA-2023)
Benferhat S, Casini G, Meyer T, Tettamanzi Agb
Proceedings of 1st Workshop on AI-driven heterogeneous data management: Completing, merging, handling inconsistencies and query-answering, co-located with 20th International Conference on Principles of Knowledge Representation and Reasoning (KR 2023).Source: CEUR WORKSHOP PROCEEDINGS, pp. 1-95
Benferhat S, Casini G, Meyer T, Tettamanzi Agb
Proceedings of 1st Workshop on AI-driven heterogeneous data management: Completing, merging, handling inconsistencies and query-answering, co-located with 20th International Conference on Principles of Knowledge Representation and Reasoning (KR 2023).Source: CEUR WORKSHOP PROCEEDINGS, pp. 1-95
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2024
Conference article
Open Access
Defeasible justification for KLM-style logic
Chama V., Wang S., Meyer T., Casini G.
Research in description logics (DLs) and formal ontologies has dedicated quite an effort to the investigation of the notion of explanation for DL reasoning, for example relying on the notion of justification [1]. There has also been some effort dedicated to the definition of defeasible reasoning for DLs that, contrary to the classical monotonic reasoning, is appropriate for dealing with incomplete/uncertain information. In the present paper, we extend the notion of justification to the framework of defeasible reasoning for DLs; specifically, we consider rational closure [2], an entailment relation that is of particular importance in the area of defeasible reasoning. Here we present the main theoretical results for the DL ALC, and an implementation of our solution, at the moment developed for propositional logic.Source: CEUR WORKSHOP PROCEEDINGS, vol. 3739. Bergen, Norway, 18-21/06/2024
Project(s): STARWARS
Chama V., Wang S., Meyer T., Casini G.
Research in description logics (DLs) and formal ontologies has dedicated quite an effort to the investigation of the notion of explanation for DL reasoning, for example relying on the notion of justification [1]. There has also been some effort dedicated to the definition of defeasible reasoning for DLs that, contrary to the classical monotonic reasoning, is appropriate for dealing with incomplete/uncertain information. In the present paper, we extend the notion of justification to the framework of defeasible reasoning for DLs; specifically, we consider rational closure [2], an entailment relation that is of particular importance in the area of defeasible reasoning. Here we present the main theoretical results for the DL ALC, and an implementation of our solution, at the moment developed for propositional logic.Source: CEUR WORKSHOP PROCEEDINGS, vol. 3739. Bergen, Norway, 18-21/06/2024
Project(s): STARWARS
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2010
Conference article
Restricted
Rational closure for defeasible description logics
Casini G, Straccia U
In the field of non-monotonic logics, the notion of rational closure is acknowledged as a landmark, and we are going to see that such a construction can be characterised by means of a simple method in the context of propositional logic. We then propose an application of our approach to rational closure in the field of Description Logics, an important knowledge representation formalism, and provide a simple decision procedure for this case.DOI: 10.1007/978-3-642-15675-5_9
Metrics:
Casini G, Straccia U
In the field of non-monotonic logics, the notion of rational closure is acknowledged as a landmark, and we are going to see that such a construction can be characterised by means of a simple method in the context of propositional logic. We then propose an application of our approach to rational closure in the field of Description Logics, an important knowledge representation formalism, and provide a simple decision procedure for this case.DOI: 10.1007/978-3-642-15675-5_9
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2020
Other
Open Access
Defeasible RDFS via rational closure
Casini G, Straccia U
In the field of non-monotonic logics, the notion of Rational Closure (RC) is acknowledged as a prominent approach. In recent years, RC has gained even more popularity in the context of Description Logics (DLs), the logic underpinning the semantic web standard ontology language OWL 2, whose main ingredients are classes and roles. In this work, we show how to integrate RC within the triple language RDFS, which together with OWL2 are the two major standard semantic web ontology languages. To do so, we start from ?df, which is the logic behind RDFS, and then extend it to ?df?, allowing to state that two entities are incompatible. Eventually, we propose defeasible ?df? via a typical RC construction. The main features of our approach are: (i) unlike most other approaches that add an extra non-monotone rule layer on top of monotone RDFS, defeasible ?df? remains syntactically a triple language and is a simple extension of ?df? by introducing some new predicate symbols with specific semantics. In particular, any RDFS reasoner/store may handle them as ordinary terms if it does not want to take account for the extra semantics of the new predicate symbols; (ii) the defeasible ?df? entailment decision procedure is build on top of the ?df? entailment decision procedure, which in turn is an extension of the one for ?df via some additional inference rules favouring an potential implementation; and (iii) defeasible ?df? entailment can be decided in polynomial time.DOI: 10.32079/isti-tr-2020/008
Metrics:
Casini G, Straccia U
In the field of non-monotonic logics, the notion of Rational Closure (RC) is acknowledged as a prominent approach. In recent years, RC has gained even more popularity in the context of Description Logics (DLs), the logic underpinning the semantic web standard ontology language OWL 2, whose main ingredients are classes and roles. In this work, we show how to integrate RC within the triple language RDFS, which together with OWL2 are the two major standard semantic web ontology languages. To do so, we start from ?df, which is the logic behind RDFS, and then extend it to ?df?, allowing to state that two entities are incompatible. Eventually, we propose defeasible ?df? via a typical RC construction. The main features of our approach are: (i) unlike most other approaches that add an extra non-monotone rule layer on top of monotone RDFS, defeasible ?df? remains syntactically a triple language and is a simple extension of ?df? by introducing some new predicate symbols with specific semantics. In particular, any RDFS reasoner/store may handle them as ordinary terms if it does not want to take account for the extra semantics of the new predicate symbols; (ii) the defeasible ?df? entailment decision procedure is build on top of the ?df? entailment decision procedure, which in turn is an extension of the one for ?df via some additional inference rules favouring an potential implementation; and (iii) defeasible ?df? entailment can be decided in polynomial time.DOI: 10.32079/isti-tr-2020/008
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2022
Conference article
Open Access
A rational entailment for expressive description logics via description logic programs
Casini G, Straccia U
Lehmann and Magidor's rational closure is acknowledged as a land-mark in the field of non-monotonic logics and it has also been re-formulated in the context ofDescription Logics (DLs). We show here how to model a rational form of entailment for expressive DLs, such as SROIQ, providing a novel reasoning procedure that compiles a non-monotone DL knowledge base into a description logic program(dl-program).Source: COMMUNICATIONS IN COMPUTER AND INFORMATION SCIENCE (PRINT), pp. 177-191. Durban, South Africa, 6-10/12/2021
DOI: 10.1007/978-3-030-95070-5_12
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Casini G, Straccia U
Lehmann and Magidor's rational closure is acknowledged as a land-mark in the field of non-monotonic logics and it has also been re-formulated in the context ofDescription Logics (DLs). We show here how to model a rational form of entailment for expressive DLs, such as SROIQ, providing a novel reasoning procedure that compiles a non-monotone DL knowledge base into a description logic program(dl-program).Source: COMMUNICATIONS IN COMPUTER AND INFORMATION SCIENCE (PRINT), pp. 177-191. Durban, South Africa, 6-10/12/2021
DOI: 10.1007/978-3-030-95070-5_12
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CNR IRIS | link.springer.com | ISTI Repository | CNR IRIS | CNR IRIS