A matroid M is called connected if for every pair of distinct elements f, g in M, there is a circuit containing both of them. This turns out to be equivalent to saying that there does not exist an element e in M with rank({e}) + rank(M - {e}) = rank(M) (note that <= always holds by submodularity of the rank function).
This method checks connectivity using the first definition above. The second definition generalizes to higher connectivity - cf. is3Connected. In the language of higher connectivity, a matroid is connected (in the sense of the two definitions above) if and only if it is 2-connected, i.e. has no 1-separation.
To obtain the connected components of a matroid, use components.
i1 : M = matroid graph({{0,1},{0,2},{1,2},{3,4},{4,5}})
o1 = a matroid of rank 4 on 5 elements
o1 : Matroid
|
i2 : isConnected M o2 = false |
i3 : C = components M
o3 = {a matroid of rank 1 on 1 elements, a matroid of rank 1 on 1 elements, a
------------------------------------------------------------------------
matroid of rank 2 on 3 elements}
o3 : List
|
i4 : all(C, isConnected) o4 = true |