“…Observe that for a biased graph (G, B), if B contains all cycles in G, then F (G, B) is the cycle matroid M (G) of G. We therefore view a graph as a biased graph with all cycles balanced. At the other extreme, when no cycles are balanced F (G, ∅) is the bicircular matroid of G, introduced by Simões-Pereira [9] and further investigated by Matthews [6], Wagner [10], and others (for instance, [5,7]). Frame matroids also include Dowling geometries [4] (see also [14]).…”