Agent Theories, Architectures, and Languages: A Survey <s> Meta-languages and syntactic modalities <s> Abstract : We are interested in constructing a computer agent whose behavior will be intelligent enough to perform cooperative tasks involving other agents like itself. One of the key tasks such an agent must perform is to form plans to carry out its intentions in a complex world in which other planning agents also exist. To constuct such agents, it will be necessary to address a number of issues that concern the interaction of knowledge, actions, and planning. Briefly stated, an agent at planning time must take into account what his future states of knowledge will be if he is to form plans that he can execute; and if he must incorporate the plans of other agents into his own, then he must also be able to reason about the knowledge and plans of other agents in an appropriate way. Despite the importance of this problem, there has not been a great deal of work in the area of formalizing a solution. Formalisms for both action and knowledge separately have been examined in some depth, but there have been few attempts at a synthesis. The exception to this is R.C. Moore's 1980 thesis on reasoning about knowledge and action for which a planner has been recently proposed. Moore shows how a formalism based on possible-world semantics can be used to reason about the interaction of knowledge and action. In this paper we develop an alternative formalism for reasoning about knowledge, belief, and action; we show how this formalism can be used to deal with several well-known problems, and then describe how it could be used by a plan constructing system. <s> BIB001 </s> Agent Theories, Architectures, and Languages: A Survey <s> Meta-languages and syntactic modalities <s> Abstract Agents who operate in complex environments must often construct plans on the basis of incomplete knowledge. In such situations, the successful agent must incorporate into his plans actions which obtain information. These plans are intrinsically sketchy to begin with and become more specified as the agent proceeds through his plan. A theory which allows for such flexible planning will have to provide solutions to two problems: (1) how can an agent reason that he knows how to perform an action? (Knowledge Preconditions Problem for Actions) and (2) if an agent must construct an underspecified plan due to incomplete knowledge, when can we say that he can successfully execute his plan? (Knowledge Preconditions Problem for Plans) This paper provides solutions to both these problems. We develop a robust and highly expressive theory of action and planning which allows for actions of varying granularity, primitive as well as complex acts, multi-agent plans, and partially specified plans. We demonstrate that this theory lends itself in a natural manner to solutions to the Knowledge Preconditions Problems. <s> BIB002 </s> Agent Theories, Architectures, and Languages: A Survey <s> Meta-languages and syntactic modalities <s> Over the past decade there has been a spurt of activity in the logic community around the development of logics of truth and modality. At the same time the literature in artificial intelligence has focused on the development of formalisms that can facilitate more expressive systems of knowledge representation. Raymond Turner brings the two together, putting current research in theories of truth and modalty in a context where it can be directly applied to knowledge representation in AI. The goal is to help AI researchers understand how the intelligent agents that they are developing represent and reason about what they believe, know, and hold to be true. Turner introduces various logics of truth and modality as part of a foundation for the construction of theories of knowledge representation. The development of logics of truth and syntactic modality is a recent phenomenon. Various logicians have developed semantic theories of truth that seek to come to terms with the constraints imposed by the semantic and logical paradoxes. Turner reviews the most recent and influential of these semantic theories and employs them as the basis for the development of logics of truth and modality. In particular, he provides an accessible exposition of the theories of Kripke, Gupta, Herzberger, Gilmore, Aczel, and Feferman. The logics extracted from these semantic theories are subsequently used to develop logics and theories of modality, propositions, and properties. Raymond Turner is Professor of Computing Science at the University of Essex. Contents: Reasoning Agents. Truth and Paradox. Truth through Fixpoints. Stable Truth. Frege Structures. Modal Logic. Truth in Modal Logic. Predicative Modality.Conclusions. <s> BIB003
A meta-language is one in which it is possible to represent the properties of another language. A first-order meta-language is a first-order logic, with the standard predicates, quantifiers, terms, and so on, whose domain contains formulae of some other language, called the object language. Using a meta-language, it is possible to represent a relationship between a meta-language term denoting an agent, and an object language term denoting some formula. For example, the meta-language formula Bel(Janine, d Father(Zeus, Cronos) e ) might be used to represent the example (1) the we saw earlier. The quote marks, d … e , are used to indicate that their contents are a meta-language term denoting the corresponding object-language formula. Unfortunately, meta-language formalisms have their own package of problems, not the least of which is that they tend to fall prey to inconsistency   . However, there have been some fairly successful meta-language formalisms, including those by Konolige BIB001 , Haas  , Morgenstern BIB002 , and Davies  . Some results on retrieving consistency appeared in the late 1980s    BIB003 .