Graphons and cut metric on sigma-finite measure spaces

Borgs, Chayes, Cohn and Holden (2016+) recently extended the definition of graphons from probability spaces to arbitrary $\sigma$-finite measure spaces, in order to study limits of sparse graphs. They also extended the definition of the cut metric, and proved various results on the resulting metric space. We continue this line of research and give various further results on graphons and the cut metric in this general setting, extending known results for the standard case of graphons on probability spaces. In particular, we characterize pairs of equivalent graphons, and we give new results on completeness and compactness.