 Since one key task for the notion of fundamentality is to help us articulate the view that there is a hierarchical structure to reality, it is usually assumed that the dependence relation we are dealing with must be asymmetric. Typically, the relation would also be considered transitive and irreflexive, hence producing a strict partial ordering. However, each of these formal characteristics can in fact be questioned, albeit whether this undermines the layered conception is up for debate (see Rabin  2018).[3]