 
Summary: Transversal and cotransversal matroids
via their representations.
Federico Ardila
Submitted: May 23, 2006; Accepted: Feb. 27, 2007
Mathematics Subject Classification: 05B35; 05C38; 05A99
Abstract.
It is known that the duals of transversal matroids are precisely the strict gammoids.
We show that, by representing these two families of matroids geometrically, one
obtains a simple proof of their duality.
0
This note gives a new proof of the theorem, due to Ingleton and Piff [3], that the duals
of transversal matroids are precisely the strict gammoids. Section 1 defines the relevant
objects. Section 2 presents explicit representations of the families of transversal matroids
and strict gammoids. Section 3 uses these representations to prove the duality of these
two families.
1
Matroids and duality. A matroid M = (E, B) is a finite set E, together with a nonempty
collection B of subsets of E, called the bases of M, which satisfy the following axiom: If
B1, B2 are bases and e is in B1  B2, there exists f in B2  B1 such that (B1  e) f is
a basis.
