3 research outputs found
Representing some non-representable matroids
We extend the notion of representation of a matroid to algebraic structures
that we call skew partial fields. Our definition of such representations
extends Tutte's definition, using chain groups. We show how such
representations behave under duality and minors, we extend Tutte's
representability criterion to this new class, and we study the generator
matrices of the chain groups. An example shows that the class of matroids
representable over a skew partial field properly contains the class of matroids
representable over a skew field.
Next, we show that every multilinear representation of a matroid can be seen
as a representation over a skew partial field.
Finally we study a class of matroids called quaternionic unimodular. We prove
a generalization of the Matrix Tree theorem for this class.Comment: 29 pages, 2 figure
Representing some non-representable matroids
We extend the notion of representation of a matroid to algebraic structures that we call skew partial fields. Our definition of such representations extends Tutte's definition, using chain groups. We show how such representations behave under duality and minors, we extend Tutte's representability criterion to this new class, and we study the generator matrices of the chain groups. An example shows that the class of matroids representable over a skew partial field properly contains the class of matroids representable over a skew field.
Next, we show that every multilinear representation of a matroid can be seen as a representation over a skew partial field.
Finally we study a class of matroids called quaternionic unimodular. We prove a generalization of the Matrix Tree theorem for this class
Orienting matroids representable over both GF[3] and GF[5]
For matroids representable over both GF[3] and GF[5], we provide a recipe for constructing an orientation