To give more context, B. Pierce, one of the authors of the Dropbox paper is (one of?) the main author of Unison, and also coauthor of the paper you linked. EDI

To give more context, B. Pierce, one of the authors of the Dropbox paper is (one of?) the main author of Unison, and also coauthor of the paper you linked. EDIT: The parent cited http://www.cis.upenn.edu/~bcpierce/papers/unisonspec.pdf http://www.cis.upenn.edu/~bcpierce/papers/unisonspec.pdf by Pierce in 2004, where the authors stressed the difficulty of writing a specification for a file synchronizer, in this case Unison.