Sorry for the incomplete information.
miid is the id of user accounts, dev is the id of devices,
this is a bipartite graph which miid only loggs in to devices, and devices are only logged in by miids, NO intra-type connection exists.
In principle there should be no login nodes, which are merely used to store what should in principle be stored as edge facets. But facets do not support indexing, while it’s sometimes useful to filter login timestamp.
I’m now trying to find all the miid’s which has at least one co-user (that is, one other miid which has shared the same device with the miid in consideration).