RHOG: A Refinement-Operator Library for Directed Labeled Graphs

This document provides the foundations behind the functionality provided by the $\rho$G library (https://github.com/santiontanon/RHOG), focusing on the basic operations the library provides: subsumption, refinement of directed labeled graphs, and distance/similarity assessment between directed labeled graphs. $\rho$G development was initially supported by the National Science Foundation, by the EAGER grant IIS-1551338.