-- -*- M2-comint -*- hash: 1731184636779096475

i1 : M = matroid({a,b,c,d},{{a,b},{a,c}})

o1 = a "matroid" of rank 2 on 4 elements

o1 : Matroid

i2 : for s in subsets M_* do print(toString s | " has rank " | rank_M s)
{} has rank 0
{a} has rank 1
{b} has rank 1
{a, b} has rank 2
{c} has rank 1
{a, c} has rank 2
{b, c} has rank 1
{a, b, c} has rank 2
{d} has rank 0
{a, d} has rank 1
{b, d} has rank 1
{a, b, d} has rank 2
{c, d} has rank 1
{a, c, d} has rank 2
{b, c, d} has rank 1
{a, b, c, d} has rank 2

i3 : 
