Intro to graph compression techniques for in-memory graph computation (2015) [pdf]
cs.umd.edu
cs.umd.edu
This was most likely done to satisfy that requirement to earn a MS "along the way" to a PhD.
"Submitted for the fulfillment of requirement of a Scholarly Paper for Master of Science without thesis option."
I personally hate non-dated preprints or technical reports. Only way to guess is to use max(date(ppaper) for paper in references), which may or may not be close the the actual date of writing.