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Onto-Med >> Theories >> GFO Part I Basic Principles

 
   

12.1 General Approach

Starting with a role $r$, there are two directly related notions, namely player and context.26 Each role $q$ requires a player $p$ and a context $c$. More precisely, $r$ is one-sidedly existentially dependent on $p$, and mutually existentially dependent with $c$. Two basic relations connect entities of these types: plays, denoted as $\Gplays(x,y)$, connecting a player $x$ with a role $y$,27 and role-of ($\Groleof(x,y)$), which ties a role $x$ to its context $y$. In terms of the ``standard'' role example of student, John plays the role of the student in the context of his relationship to his university. Other examples refer to John as an employee in the context of some company, or as a mover of some pen, in the context of that movement.

Moreover, apart from roles, players, and contexts, roles are often contrasted with natural universals28, cf. (27). While ``student'' is a role, ``human'' is not a role, but a natural universal that provides players for roles. Intuitively, roles can be distinguished from natural universals by their dependence on a context, whereas for natural universals, the context of the considered role is irrelevant.

Each of these categories discussed thus far are self-contained, in the sense that they do not provide insights on how they are related to other GFO categories in this work. To establish these links, we first note that there are individuals as well as categories of roles (and all other notions). For more specific relations, different types of roles need to be distinguished. This classification is based on the contexts of roles, because the coupling of roles and contexts is more tight than between players and roles, cf. (37).

Robert Hoehndorf 2006-10-18
 
       
     
     
     

   
     
     
       
 

deutsch   imise uni-leipzig ifi dep-of-formal-concepts