A graph is simple if it is both loop free, and parallel free. See also
IsLoopFree and IsParallelFree.
IsSimpleGraph(arcSources, arcTargets, numNodes)TRUE if graph is simple, FALSE otherwise.
Vector corresponding to the source nodes of a graph's edges
Vector corresponding to the destination nodes of a graph's edges
The number of nodes in the graph
See https://lemon.cs.elte.hu/pub/doc/1.3.1/a00616.html#gae4c7ae734e2509ab78dc747d602c9236 for more information.