  Most graph query languages are rooted in logic. By contrast, in this paper we
consider graph query languages rooted in linear algebra. More specifically, we
consider MATLANG, a matrix query language recently introduced, in which some
basic linear algebra functionality is supported. We investigate the problem of
characterising equivalence of graphs, represented by their adjacency matrices,
for various fragments of MATLANG. A complete picture is painted of the impact
of the linear algebra operations in MATLANG on their ability to distinguish
graphs.
