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                * Princeton Discrete Math Seminar *
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Date: Thursday 11th April, 4:30 in Fine Hall 224.
 
Speaker: Vaidy Sivaraman (Binghamton University)

Title: Transversal signed-graphic matroids

Abstract: Signed-graphic matroids are a genuine generalization of graphic
matroids, and a lot of research has been done on determining to what extent 
we can transfer properties of graphic matroids to signed-graphic matroids. 
In this talk we focus on two theorems from the 1970s. The first one, due to
Matthews, characterizes graphs whose bicircular matroids are graphic. We
characterize graphs whose bicircular matroids are signed-graphic. The
second one, due to Bondy and Las Vergnas, characterizes graphs whose cycle
matroids are transversal. We attempt to characterize signed graphs whose
frame matroids are transversal. Time permitting, we will discuss the issue
of basis counting in different classes of matroids, and progress on a
related conjecture of Welsh.

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Next week:  Esther Ezra (NYU)

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