Applied Ontology

There are two main traditions in defining a semantics for agent communication languages, based either on mental attitudes or on social commitments. These traditions share speech acts as operators with preconditions and effects, and agents playing roles like speaker and hearer, but otherwise they rely on distinct ontologies. They refer not only to either belief and intention or various notions of social commitment, but also to distinct speech acts and distinct kinds of dialogue. In this paper, we propose a common ontology for both approaches based on public mental attitudes attributed to role instances. Public mental attitudes avoid the unverifiability problem of private mental states, while reusing the logics and implementations developed for FIPA compliant approaches. Moreover, a common ontology of communication primitives allows for the construction of agents which do not need separate reasoning modules to participate in dialogues with both mental attitudes and social commitments compliant agents. Moreover, a common ontology of communication primitives allows for the construction of agents participating in and combining the full range of dialogues covered by the individual approaches without having to redefine the existing protocols to cope with new dialog types. We illustrate how to extend the ontology to a semantics for agent communication and how to define mappings from existing semantics to the new one.

In open heterogeneous multi-agent systems, communication is hampered by lack of common ontologies. Ontologies may differ in naming conventions, granularity and scope. In such an environment, the agents must possess the right conversational skills to effectively exchange information even when the speaker's ontology is only approximately translatable to the hearer's ontology. Furthermore, the agents must be able to autonomously establish an ontology translation by exchanging parts of their ontologies. In this paper, we propose a layered communication protocol in which the agents gradually build towards a semantically integrated system by establishing minimal and effective common ontologies. We tested our system, called ANEMONE, on a number of heterogeneous news agents. We show how these agents successfully exchange information on news articles, despite initial difficulties caused by heterogeneous ontologies.

In open scenarios, agents willing to cooperate must impact the communication barrier between them and their unknown partners. If agents are not relying on any agreement about the meaning they ascribe to the symbols used in the conversation, semantic misalignments will arise on the discourse domain as well, thus making the communication impossible. In wide and heterogeneous scenarios offered by the Web (and its newborn semantic incarnation), traditional and meaning-safe methodologies for communication need to keep abreast of new dynamic communicative interaction modalities. The uncertainties arising from communication between actors which base their behavior on different and heterogeneous knowledge models have to be taken into account, wisely balancing the extent of “reachable knowledge” with the trustworthiness of its information. Main objective of this work is to augment the FIPA Ontology Service Specification with linguistically-aware methodologies for communication, describing a wide-scope framework for multi-agent systems design, semantic integration and coordination.

A fundamental interoperability problem is caused by the semantic heterogeneity of agents'ontologies in open multi-agent systems. In this paper, we propose a formal framework for agents debating over heterogeneous terminologies. For this purpose, we propose an argumentation-based representation framework to manage conflicting descriptions. Moreover, we propose a model for the reasoning of agents where they justify the description to which they commit and take into account the description of their interlocutors. Finally, we provide a dialectical system allowing agents to participate in a dialogue in order to reach an agreement over heterogeneous descriptions.

This paper presents a formal ontology which intends to facilitate interoperability among agents belonging to software agent systems that use different agent communication languages. The followed design criteria for building the ontology are an elaboration on the “illocutionary force-plus-content” framework of speech acts theory. The ontology is specified in OWL. Reasons are presented through the paper why, in our opinion, an ontology based on speech acts theory and specified in a DL-based language is adequate for formal agent communication. The ontology is divided into three layers: upper, standards and applications, grouping classes by different levels of abstraction. The formalism used in the specification of classes allows automated reasoning for locating classes in the taxonomy and recognizing individuals of classes.

This work introduces a formal framework for the social acquisition of ontologies which are constructed dynamically from overhearing the possibly conflicting symbolic interaction of autonomous information sources, and an approach to the pragmatics of communicated ontological axioms. Technically, the framework is based on distributed variants of description logic for the formal contextualization of statements w.r.t. their respective provenance, speaker's attitude, addressees, and subjective degree of confidence. Doing so, our approach demarcates from the dominating more or less informal approaches to context and provenance representation on the semantic web, and carefully distinguishes between communication attitudes such as public assertion and intention exhibited on the (semantic) web on the one hand, and mental attitudes such as private belief on the other. Furthermore, our framework provides formal means for the probabilistic fusion of controversial opinions, and presents a semantics of information publishing acts. Our approach provides an incomplex and genuinely social approach to knowledge acquisition and representation, and is thus expected to be widely applicable in fields such as the semantic web and social software, and possibly also in other distributed environments such as P2P systems.