"Conflict-free replicated data type" https://en.wikipedia.org/wiki/Conflict-free_replicated_data_type
"A comprehensive study of CRDTs" http://hal.upmc.fr/inria-00555588/document (original CRDT paper by Shapiro, Pregui, Baquero, Zawirski)
"CRDTs: Distributed Semilattices" http://blog.plasmaconduit.com/crdts-distributed-semilattices/