We now want to recapitulate the discussion on temporal join conditions in section 4.1 and focus on the way in which they can be decomposed. Previously, we classified temporal joins according to their corresponding temporal join conditions. Thus, when speaking about decomposing a certain class/type of temporal join we often refer to the decomposition of the underlying join condition (and vice versa). There is a set of elementary (i.e. non-decomposable) temporal joins / join conditions which is presented in section 11.2.1. On top of these, several composite conditions can be created, in particular those that arise from Allen's interval relationships (see section 11.2.2). We note that the classification scheme used here differs slightly from the one in section 4.1 because we focus on whether a condition is elementary or composite.