A perfect illustration of such an approach is the work on spatial logic, see Aiello et al. (2007) for an excellent overview. The authors compare their approach to the work done in temporal logic (see the entry on temporal logic in this encyclopedia). There are plenty of ways to model time: with a starting and/or final point, discrete or continuous, linear, cyclic or branching, …. The logical task is to construct a language that allows one to “talk” about all these structures and to be able to differentiate between them. In temporal logic such a language uses the operators \(Fp\) (“I will be the case that \(p\)”) and \(Pp\) (“It has been the case that \(p\)”). One example: if time is linear in the future, then this property can be expressed as follows. Suppose that \(Fp\) and \(Fq\) are given, then only three things are possible: either \(F(p \amp q)\), i.e., \(p\) and \(q\) will be the case, or \(F(p \amp Fq)\), i.e., \(p\) will happen first and then \(q\), or \(F(Fp \amp q)\), i.e., the other way round.  In one formula: \((Fp \amp Fq) \rightarrow (F(p \amp q)\) or \(F(p \amp Fq)\) or \(F(Fp \amp q))\). In an entirely similar way, to construct such a language is what spatial logic wants to achieve for geometry and is thus related to the proposals that we will discuss in section 3.