Initially, situation semantics was conceived as essentially synthetic, with a mathematical ontology built up on set theory. Soon after the appearance of [4], however, the authors changed their approach and decided to handle the topic in an analytic fashion, abstracting a mathematical ontology from analyses of natural language use. Situation theory is the name they gave to the underlying mathema...

Dyna is an AI architecture that integrates learning, planning, and reactive execution. Learning methods are used in Dyna both for compiling planning results and for updating a model of the eeects of the agent's actions on the world. Planning is incre-mental and can use the probabilistic and ofttimes incorrect world models generated by learning processes. Execution is fully reactive in the sense...

In a seminal paper Lin and Reiter introduced the notion of progression for basic action theories in the situation calculus. The idea is to replace an initial database by a new set of sentences which reflect the changes due to an action. Unfortunately, progression requires secondorder logic in general. In this paper, we introduce the notion of strong progression, a slight variant of Lin and Reit...

A fundamental task in reasoning about action and change is projection, which refers to determining what holds after a number of actions have occurred. A powerful method for solving the projection problem is regression, which reduces reasoning about the future to reasoning about the initial state. In particular, regression has played an important role in the situation calculus and its epistemic ...

We define a notion of bounded action theory in the situation calculus, where the theory entails that in all situations, the number of ground fluent atoms is bounded by a constant. Such theories can still have an infinite domain and an infinite set of states. We argue that such theories are fairly common in applications, either because facts do not persist indefinitely or because one eventually ...

We propose a translation into Modal Logic of the ideas that formalise belief change in the Situation Calculus. This translation is extended to the case of revision. In the conclusion is presented a set of open issues.

Computers will probably never achieve the level of human skills in natural language processing, but they can well aid in such actions as searching in a database. The project NALOG – NAtural language processing and LOGic programming – aims at querying a database in natural language and getting answers in natural language again. As query language and internal representation format, we explore the...