-- -*- M2-comint -*- hash: 923053991446741528

i1 : A = matrix{{1,1,0},{-1,0,1},{0,-1,-1}}

o1 = | 1  1  0  |
     | -1 0  1  |
     | 0  -1 -1 |

              3       3
o1 : Matrix ZZ  <-- ZZ

i2 : arr = arrangement A

o2 = {x  - x , x  - x , x  - x }
       1    2   1    3   2    3

o2 : Hyperplane Arrangement 

i3 : matroid arr

o3 = a "matroid" of rank 2 on 3 elements

o3 : Matroid

i4 : 
