Autonomous intelligent agents are playing increasingly important roles in our lives. They contain... more Autonomous intelligent agents are playing increasingly important roles in our lives. They contain information about us and start to perform tasks on our behalves. Chatbots are an example of such agents that need to engage in a complex conversations with humans. Thus, we need to ensure that they behave ethically. In this work we propose a hybrid logic-based approach for ethical chatbots.
In artificial intelligence, multi agent systems constitute an interesting typology of society mod... more In artificial intelligence, multi agent systems constitute an interesting typology of society modeling, and have in this regard vast fields of application, which extend to the human sciences. Logic is often used to model such kind of systems as it is easier to verify than other approaches, and provides explainability and potential validation. In this paper we define a time module suitable to add time to many logic representations of agents.
DALI is a logic programming agent-oriented language defined in [1,2,3,4] and for-malized in [5,6,... more DALI is a logic programming agent-oriented language defined in [1,2,3,4] and for-malized in [5,6,7]. DALI has been implemented, and has been used in several (also industrial) applications [8,9,10,11,12,13,14,15,16,17,18,19]. A stable but not recent re-lease of the DALI interpreter is publicly available at [20]. Latest releases are available upon request. DALI provides external, internal and events, reactivity and proactivity, a flexible communication architecture including a filter upon communications, and more additional features which have been developed over time [21]. For the definition of DALI we have built upon our past work about meta-reasoning and reflection in logic programming languages [22,23,24,25,26]. Semantics of such constructs is provided by means of Reflection Principles [26], inspired to the ones in-troduced in Symbolic Logic by Feferman in 1962. The operational semantics consists in an extended resolution procedure [23,24]. In [1,2,3] one can find the basic defini...
Abstract. This paper presents a logic programming language of novel conception, called Reflective... more Abstract. This paper presents a logic programming language of novel conception, called Reflective Prolog, which allows declarative metaknowledge representation and metareasoning. The language is defined by augmenting pure Prolog (Horn clauses) with capabilities of self-reference and logical reflection. Self-reference is designed as a quotation device (a carefully defined naming relation) which allows the construction of metalevel terms that refer to objectlevel terms and atoms. Logical reffection is designed as an unquotation mechanism (a distinguished truth predicate) which relates names to what is named, thus extending the meaning of domain predicates. The reflection mechanism is embodied in an extended resolution procedure which automatically switches the context between levels. This implicit reflection relieves the programmer from having to explicitly deal with control aspects of the inference process. The declarative semantics of a Reflective Prolog definite program P is provid...
Integration of data is required when accessing multiple databases within an organization or on th... more Integration of data is required when accessing multiple databases within an organization or on the WWW. Schema integration is required for database interoperability, but it is currently, a manual process. The so-called Global-as-View approach constitutes an effective proposal for the design of data integration systems. The combination of diverse database schemata into an integrated view is achieved by means of a global conceptual data model. Consequently, the user is provided with a unified view of the data and (s)he can query such a global schema ignoring the location and structure of the data sources. However, data integration involves resolving conflicts. Schema conflicts include naming, structural, and semantic conflicts. Then, when trying to answer a query in a data integration system, various forms of incompleteness and/or uncertainty may arise. This work aims at demonstrating that Answer Set Programming is a suitable paradigm for defining and implementing data integration sys...
In this paper we present the new logic programming language DALI, aimed at defining agents and ag... more In this paper we present the new logic programming language DALI, aimed at defining agents and agent systems. A main design objective for DALI has been that of introducing in a declarative fashion all the essential features, while keeping the language as close as possible to the syntax and semantics of the plain Horn--clause language. Special atoms and rules have been introduced, for representing: external events, to which the agent is able to respond (reactivity); actions (reactivity and proactivity); internal events (previous conclusions which can trigger further activity); past and present events (to be aware of what has happened). An extended resolution is provided, so that a DALI agent is able to answer queries like in the plain Horn--clause language, but is also able to cope with the different kinds of events, and exhibit a (rational) reactive and proactive behaviour.
Methods for implementing Automated Reasoning in a fashion that is at least reminiscent of human c... more Methods for implementing Automated Reasoning in a fashion that is at least reminiscent of human cognition and behavior must refer (also) to Intelligent Agents. In fact they implement many important autonomous applications upon which, nowadays, the life and welfare of living beings may depend. In such contexts, ’humanized’ agents should do what is expected of them, but perhaps more importantly they should not behave in improper/unethical ways given the present context. We propose techniques for introspective selfmonitoring and checking.
From a logic programming point of view, the stable model semantics for normal programs has the pr... more From a logic programming point of view, the stable model semantics for normal programs has the problem that logical consequences of programs cannot, in general, be stored as lemmas. This is because the set of stable models of the resulting program may change. In fact, logical consequence under the stable model semantics does not enjoy an important property required of non–monotonic entailment relations, i.e. cumulativity. We argue that it is possible to assert a conclusion A as a lemma in the stable model semantics, if asserting at the same time a set of facts supporting the conclusion (that we call a base set for A). The effect on the meaning of the program is that of selecting some of the stable models containing A. The collection of all base sets for A generates all the stable models containing A. We formalize this intuition by reformulating the definition of cumulativity accordingly. We propose a characterization of base sets that identifies the minimal ones, i.e. the fewest and...
Chatbot is an artificial intelligent software which can simulate a conversation with a user in na... more Chatbot is an artificial intelligent software which can simulate a conversation with a user in natural language via auditory or textual methods. Businesses are rapidly moving towards the need for chatbots. However chatbots raise many ethical concerns. To ensure that they behave ethically, their behavior should be guided by the codes of ethics and conduct of their company.
Digital Forensics is a branch of criminalistics which deals with the identification, acquisition,... more Digital Forensics is a branch of criminalistics which deals with the identification, acquisition, preservation, analysis and presentation of the information content of digital devices. In this paper, we briefly describe DigForASP, a COST Action that aims to create a cooperation network for exploring the potential of the application of techniques from the field of Artificial Intelligence, in particular from the area of Knowledge Representation and Reasoning, in the Digital Forensics field, and to foster synergies between these fields. More precisely, in DigForASP the challenge is to address the so-called Evidence Analysis phase, where evidence about possible crimes and crimes’ perpetrators must be exploited so as to reconstruct possible events, event sequences and scenarios related to a crime. Results from this phase are then made available to the involved stakeholders (law enforcement, investigators, public prosecutors, lawyers and judges). Reliability, explainability and verifiabil...
Communication and interaction among agents have been the subject of extensive investigation since... more Communication and interaction among agents have been the subject of extensive investigation since many years. Commitment-based communication, where communicating agents are seen as a debtor agent who is committed to a creditor agent to bring about something (possibly under some conditions) is now very well-established. The approach of DACMAS (Data-Aware Commitment-based MAS) lifts commitment-related approaches proposed in the literature from a propositional to a first-order setting via the adoption the DRL-Lite Description Logic. Notably, DACMASs provide, beyond commitments, simple forms of inter-agent event-based communication. Yet, the aspect is missing of making a MAS able to acquire knowledge from contexts which are not agents and which are external to the MAS. This topic is coped with in Managed MCSs (Managed Multi-Context Systems), where however exchanges are among knowledge bases and not agents. In this paper, we propose the new approach of DACmMCMASs (Data-Aware Commitment-b...
In this paper we consider complex application scenarios, typically concerning smart Cyber-Physica... more In this paper we consider complex application scenarios, typically concerning smart Cyber-Physical Systems, where several components and subsystems interact among themselves, with human users and with the physical environment, and employ forms of intelligent reasoning for meeting the system’s requirements and reaching its overall objectives. We propose a new multi-component multi-level architecture called K-ACE, which provides a high degree of flexibility in the system’s definition, though within a formal semantics.
In this paper we consider the software-engineering problem of how to empower modular agent archit... more In this paper we consider the software-engineering problem of how to empower modular agent architectures with the capability to perform quantitative reasoning in a uniform and principled way.
We build upon recent work by Baral, Dzifcak and Son that define the translation into ASP of (some... more We build upon recent work by Baral, Dzifcak and Son that define the translation into ASP of (some classes of) natural language sentences from the lambda-calculus intermediate format generated by CCG grammars. We introduce automatic generation of lambda-calculus expressions from template ones, thus improving the effectiveness and generality of the translation process.
In this paper we consider Epistemic Logic Programs (ELPs), which extend Answer Set Programming (A... more In this paper we consider Epistemic Logic Programs (ELPs), which extend Answer Set Programming (ASP) with “epistemic operators”. There are several approaches to the semantics of such programs in terms of World Views, which are sets of belief sets. Recent work has proposed an analysis of the structure of ELPs in terms of a concept of “splitting”, in order to be able to modularly compute their semantics in a bottom-up fashion, analogously to ‘traditional’ ASP. The proposal is brilliant but the problem is, that few of the semantics that have been proposed so far enjoy this new “Epistemic Splitting Property”. Thus, the notion of modular computation of world views does not work for most of the cases. We analyse the possibility to change the perspective about how to exploit a splitting, shifting from a bottom-up to a top-down approach. Our new definition: (i) copes with concerns regarding, e.g. “unfoundedness” of world views and “subjective constraint monotonicity”; (ii) is applicable to ...
The results of the evidence analysis phase in Digital Forensics (DF) provide objective data which... more The results of the evidence analysis phase in Digital Forensics (DF) provide objective data which however require further elaboration by the investigators, that have to contextualize analysis results within an investigative environment so as to provide possible hypotheses that can be proposed as proofs in court, to be evaluated by lawyers and judges. Aim of our research has been that of exploring the applicability of Answer Set Programming (ASP) to the automatization of evidence analysis. This offers many advantages, among which that of making different possible investigative hypotheses explicit, while otherwise different human experts often devise and select different solutions in an implicit way. Moreover, ASP provides a potential for verifiability which is crucial in such an application field. Very complex investigations for which human experts can hardly find solutions turn out in fact to be reducible to optimization problems in classes P or NP or not far beyond, that can be thu...
Autonomous intelligent agents are playing increasingly important roles in our lives. They contain... more Autonomous intelligent agents are playing increasingly important roles in our lives. They contain information about us and start to perform tasks on our behalves. Chatbots are an example of such agents that need to engage in a complex conversations with humans. Thus, we need to ensure that they behave ethically. In this work we propose a hybrid logic-based approach for ethical chatbots.
In artificial intelligence, multi agent systems constitute an interesting typology of society mod... more In artificial intelligence, multi agent systems constitute an interesting typology of society modeling, and have in this regard vast fields of application, which extend to the human sciences. Logic is often used to model such kind of systems as it is easier to verify than other approaches, and provides explainability and potential validation. In this paper we define a time module suitable to add time to many logic representations of agents.
DALI is a logic programming agent-oriented language defined in [1,2,3,4] and for-malized in [5,6,... more DALI is a logic programming agent-oriented language defined in [1,2,3,4] and for-malized in [5,6,7]. DALI has been implemented, and has been used in several (also industrial) applications [8,9,10,11,12,13,14,15,16,17,18,19]. A stable but not recent re-lease of the DALI interpreter is publicly available at [20]. Latest releases are available upon request. DALI provides external, internal and events, reactivity and proactivity, a flexible communication architecture including a filter upon communications, and more additional features which have been developed over time [21]. For the definition of DALI we have built upon our past work about meta-reasoning and reflection in logic programming languages [22,23,24,25,26]. Semantics of such constructs is provided by means of Reflection Principles [26], inspired to the ones in-troduced in Symbolic Logic by Feferman in 1962. The operational semantics consists in an extended resolution procedure [23,24]. In [1,2,3] one can find the basic defini...
Abstract. This paper presents a logic programming language of novel conception, called Reflective... more Abstract. This paper presents a logic programming language of novel conception, called Reflective Prolog, which allows declarative metaknowledge representation and metareasoning. The language is defined by augmenting pure Prolog (Horn clauses) with capabilities of self-reference and logical reflection. Self-reference is designed as a quotation device (a carefully defined naming relation) which allows the construction of metalevel terms that refer to objectlevel terms and atoms. Logical reffection is designed as an unquotation mechanism (a distinguished truth predicate) which relates names to what is named, thus extending the meaning of domain predicates. The reflection mechanism is embodied in an extended resolution procedure which automatically switches the context between levels. This implicit reflection relieves the programmer from having to explicitly deal with control aspects of the inference process. The declarative semantics of a Reflective Prolog definite program P is provid...
Integration of data is required when accessing multiple databases within an organization or on th... more Integration of data is required when accessing multiple databases within an organization or on the WWW. Schema integration is required for database interoperability, but it is currently, a manual process. The so-called Global-as-View approach constitutes an effective proposal for the design of data integration systems. The combination of diverse database schemata into an integrated view is achieved by means of a global conceptual data model. Consequently, the user is provided with a unified view of the data and (s)he can query such a global schema ignoring the location and structure of the data sources. However, data integration involves resolving conflicts. Schema conflicts include naming, structural, and semantic conflicts. Then, when trying to answer a query in a data integration system, various forms of incompleteness and/or uncertainty may arise. This work aims at demonstrating that Answer Set Programming is a suitable paradigm for defining and implementing data integration sys...
In this paper we present the new logic programming language DALI, aimed at defining agents and ag... more In this paper we present the new logic programming language DALI, aimed at defining agents and agent systems. A main design objective for DALI has been that of introducing in a declarative fashion all the essential features, while keeping the language as close as possible to the syntax and semantics of the plain Horn--clause language. Special atoms and rules have been introduced, for representing: external events, to which the agent is able to respond (reactivity); actions (reactivity and proactivity); internal events (previous conclusions which can trigger further activity); past and present events (to be aware of what has happened). An extended resolution is provided, so that a DALI agent is able to answer queries like in the plain Horn--clause language, but is also able to cope with the different kinds of events, and exhibit a (rational) reactive and proactive behaviour.
Methods for implementing Automated Reasoning in a fashion that is at least reminiscent of human c... more Methods for implementing Automated Reasoning in a fashion that is at least reminiscent of human cognition and behavior must refer (also) to Intelligent Agents. In fact they implement many important autonomous applications upon which, nowadays, the life and welfare of living beings may depend. In such contexts, ’humanized’ agents should do what is expected of them, but perhaps more importantly they should not behave in improper/unethical ways given the present context. We propose techniques for introspective selfmonitoring and checking.
From a logic programming point of view, the stable model semantics for normal programs has the pr... more From a logic programming point of view, the stable model semantics for normal programs has the problem that logical consequences of programs cannot, in general, be stored as lemmas. This is because the set of stable models of the resulting program may change. In fact, logical consequence under the stable model semantics does not enjoy an important property required of non–monotonic entailment relations, i.e. cumulativity. We argue that it is possible to assert a conclusion A as a lemma in the stable model semantics, if asserting at the same time a set of facts supporting the conclusion (that we call a base set for A). The effect on the meaning of the program is that of selecting some of the stable models containing A. The collection of all base sets for A generates all the stable models containing A. We formalize this intuition by reformulating the definition of cumulativity accordingly. We propose a characterization of base sets that identifies the minimal ones, i.e. the fewest and...
Chatbot is an artificial intelligent software which can simulate a conversation with a user in na... more Chatbot is an artificial intelligent software which can simulate a conversation with a user in natural language via auditory or textual methods. Businesses are rapidly moving towards the need for chatbots. However chatbots raise many ethical concerns. To ensure that they behave ethically, their behavior should be guided by the codes of ethics and conduct of their company.
Digital Forensics is a branch of criminalistics which deals with the identification, acquisition,... more Digital Forensics is a branch of criminalistics which deals with the identification, acquisition, preservation, analysis and presentation of the information content of digital devices. In this paper, we briefly describe DigForASP, a COST Action that aims to create a cooperation network for exploring the potential of the application of techniques from the field of Artificial Intelligence, in particular from the area of Knowledge Representation and Reasoning, in the Digital Forensics field, and to foster synergies between these fields. More precisely, in DigForASP the challenge is to address the so-called Evidence Analysis phase, where evidence about possible crimes and crimes’ perpetrators must be exploited so as to reconstruct possible events, event sequences and scenarios related to a crime. Results from this phase are then made available to the involved stakeholders (law enforcement, investigators, public prosecutors, lawyers and judges). Reliability, explainability and verifiabil...
Communication and interaction among agents have been the subject of extensive investigation since... more Communication and interaction among agents have been the subject of extensive investigation since many years. Commitment-based communication, where communicating agents are seen as a debtor agent who is committed to a creditor agent to bring about something (possibly under some conditions) is now very well-established. The approach of DACMAS (Data-Aware Commitment-based MAS) lifts commitment-related approaches proposed in the literature from a propositional to a first-order setting via the adoption the DRL-Lite Description Logic. Notably, DACMASs provide, beyond commitments, simple forms of inter-agent event-based communication. Yet, the aspect is missing of making a MAS able to acquire knowledge from contexts which are not agents and which are external to the MAS. This topic is coped with in Managed MCSs (Managed Multi-Context Systems), where however exchanges are among knowledge bases and not agents. In this paper, we propose the new approach of DACmMCMASs (Data-Aware Commitment-b...
In this paper we consider complex application scenarios, typically concerning smart Cyber-Physica... more In this paper we consider complex application scenarios, typically concerning smart Cyber-Physical Systems, where several components and subsystems interact among themselves, with human users and with the physical environment, and employ forms of intelligent reasoning for meeting the system’s requirements and reaching its overall objectives. We propose a new multi-component multi-level architecture called K-ACE, which provides a high degree of flexibility in the system’s definition, though within a formal semantics.
In this paper we consider the software-engineering problem of how to empower modular agent archit... more In this paper we consider the software-engineering problem of how to empower modular agent architectures with the capability to perform quantitative reasoning in a uniform and principled way.
We build upon recent work by Baral, Dzifcak and Son that define the translation into ASP of (some... more We build upon recent work by Baral, Dzifcak and Son that define the translation into ASP of (some classes of) natural language sentences from the lambda-calculus intermediate format generated by CCG grammars. We introduce automatic generation of lambda-calculus expressions from template ones, thus improving the effectiveness and generality of the translation process.
In this paper we consider Epistemic Logic Programs (ELPs), which extend Answer Set Programming (A... more In this paper we consider Epistemic Logic Programs (ELPs), which extend Answer Set Programming (ASP) with “epistemic operators”. There are several approaches to the semantics of such programs in terms of World Views, which are sets of belief sets. Recent work has proposed an analysis of the structure of ELPs in terms of a concept of “splitting”, in order to be able to modularly compute their semantics in a bottom-up fashion, analogously to ‘traditional’ ASP. The proposal is brilliant but the problem is, that few of the semantics that have been proposed so far enjoy this new “Epistemic Splitting Property”. Thus, the notion of modular computation of world views does not work for most of the cases. We analyse the possibility to change the perspective about how to exploit a splitting, shifting from a bottom-up to a top-down approach. Our new definition: (i) copes with concerns regarding, e.g. “unfoundedness” of world views and “subjective constraint monotonicity”; (ii) is applicable to ...
The results of the evidence analysis phase in Digital Forensics (DF) provide objective data which... more The results of the evidence analysis phase in Digital Forensics (DF) provide objective data which however require further elaboration by the investigators, that have to contextualize analysis results within an investigative environment so as to provide possible hypotheses that can be proposed as proofs in court, to be evaluated by lawyers and judges. Aim of our research has been that of exploring the applicability of Answer Set Programming (ASP) to the automatization of evidence analysis. This offers many advantages, among which that of making different possible investigative hypotheses explicit, while otherwise different human experts often devise and select different solutions in an implicit way. Moreover, ASP provides a potential for verifiability which is crucial in such an application field. Very complex investigations for which human experts can hardly find solutions turn out in fact to be reducible to optimization problems in classes P or NP or not far beyond, that can be thu...
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