Objectives

The main objective of this thesis is an in depth analysis of situations as an ontological category. The category situation as well as all other categories needed to understand it, states of affairs, infons, actions or events, shall be investigated and the findings should be put in axioms as far as possible. These axioms should extend the axioms of the ontologies of GOL, or replace them if necessary. In the end, a theory of situations has to be developed within GOL or some modified version of GOL, which has at least the same expressive power as Situation Theory, a formalism developed by Jon Barwise and John Perry, for example in barsit. To achieve this, Situation Theory and its axioms can be used as a background, but should be extended, altered or in parts rejected when necessary, in order to obtain a philosophically well founded description of the category situation. If parts of Situation Theory are copied into GOL, it has to be shown that these parts are appropriate.

Before situations can be analyzed, the more basic categories of facts or states of affairs have to be analyzed. It is believed that states of affairs can be viewed as basic information units, or infons, that are used to communicate information, or express information present in a situation. A category of facts does exist in GOL, but the instances of this category are not information units. Another objective of this thesis is to reexamine the GOL category of facts and analyze whether it is suited to be used together with the category of situations. If not, it has to be modified or extended accordingly.

In the analysis of situations, the concept of ``being comprehensible as a whole'' will be central. It has to be analyzed thoroughly, and, as far as possible, axioms have to be formalized for it, so it can be applied to different entities as well.

Other entities that may be related to situations, like universals, sets, processes, changes, etc. can be more thoroughly understood, and if adequate, some of their properties can be deduced from the properties of situations.

There are still some ontological categories or relations in GOL, that require clarification. Some are clearly understood and axiomatized, but GOL does not provide the means to specify an instance of this category. If adequate, this thesis will provide hints or solutions to some of these questions.