Some basics II

[Gordon]

Some more questions based on the following data - basically, what is determining the time taken?

Is there a reason why has_minor does not call has_field_minor if both matroids are BinaryMatroids?

sage: pet_regular = Matroid(graphs.PetersenGraph())
sage: pet_basis = BasisMatroid(pet_regular)
sage: pet_binary = BinaryMatroid(pet_regular.representation())
sage: fano_binary = matroids.named_matroids.Fano()
sage: fano_basis = BasisMatroid(fano_binary)

sage: %time pet_regular.has_minor(fano_binary)
CPU times: user 8.16 s, sys: 0.01 s, total: 8.16 s
Wall time: 8.16 s
False
sage: %time pet_regular.has_minor(fano_basis)
CPU times: user 8.12 s, sys: 0.00 s, total: 8.12 s
Wall time: 8.12 s
False
sage: %time pet_binary.has_minor(fano_binary)
CPU times: user 6.51 s, sys: 0.06 s, total: 6.57 s
Wall time: 6.52 s
False
sage: %time pet_binary.has_minor(fano_basis)
CPU times: user 6.66 s, sys: 0.00 s, total: 6.66 s
Wall time: 6.66 s
False
sage: %time pet_basis.has_minor(fano_basis)
CPU times: user 10.21 s, sys: 0.00 s, total: 10.22 s
Wall time: 10.22 s
False
sage: %time pet_basis.has_minor(fano_binary)
CPU times: user 14.74 s, sys: 0.01 s, total: 14.75 s
Wall time: 14.75 s
False
sage: pet_binary.has_field_minor(fano_binary)
False
sage: %time pet_binary.has_field_minor(fano_binary)
CPU times: user 3.16 s, sys: 0.04 s, total: 3.19 s
Wall time: 3.16 s
False