As explained in Chapter 4,
-indistinguishability operators have a very important metric component. One consequence of this fact is that, if the t-norm is continuous Archimedean, the operators generate metric betweenness relations and their structure can be studied in terms of the different types of betweenness relations they produce. This chapter will revisit the three main methods for building
-indistinguishability operators -with the sup-
product, using the Representation Theorem and by constructing a decomposable relation from a fuzzy subset- in relation to betweenness relations.