2019-05-13 13:26:20 +0200 | asked a question | Concern about output from intersection_poset method The output from the intersection_poset command concerns me. I typed the following H5 = HyperplaneArrangements(QQ, ('x1', 'x2', 'x3', 'x4', 'x5')) where the last command prints out the (Hasse diagram of) intersection poset of C5. My direct calculation tells me that all of the rank-2 elements should be the joins of 3 atoms (rank-1 elements). Perhaps the discrepancy is due to linear dependence between the hyperplanes in C5. For instance, note that the second coefficient vector is the sum of the first and fourth. I running SageMath 8.0. Perhaps this was fixed in some later version--I will seek an upgrade. |

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