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positiveOrientation -- a positive orientation of a matroid

Synopsis

Description

This function computes a relabelling of the ground set of a matroid for which it is positively oriented, if one exists. In other words, the output of this function is null iff the output of isPositivelyOrientable is false.

i1 : M = matroid({{0,1},{2,3},{4,5}}, EntryMode => "circuits")

o1 = a "matroid" of rank 3 on 6 elements

o1 : Matroid
 
i2 : isPositivelyOriented M

o2 = false
 
i3 : p = positiveOrientation M

o3 = {0, 5, 1, 4, 2, 3}

o3 : List
 
i4 : N = relabel(M, p)

o4 = a "matroid" of rank 3 on 6 elements

o4 : Matroid
 
i5 : isPositivelyOriented N

o5 = true

See also

Ways to use positiveOrientation:

For the programmer

The object positiveOrientation is a method function.