The Michigan Mathematical Journal

A Note on Brill–Noether Existence for Graphs of Low Genus

Stanislav Atanasov and Dhruv Ranganathan

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In an influential 2008 paper, Baker proposed a number of conjectures relating the Brill–Noether theory of algebraic curves with a divisor theory on finite graphs. In this note, we examine Baker’s Brill–Noether existence conjecture for special divisors. For g5 and ρ(g,r,d) nonnegative, every graph of genus g is shown to admit a divisor of rank r and degree at most d. As further evidence, the conjecture is shown to hold in rank 1 for a number families of highly connected combinatorial types of graphs. In the relevant genera, our arguments give the first combinatorial proof of the Brill–Noether existence theorem for metric graphs, giving a partial answer to a related question of Baker.

Article information

Michigan Math. J., Volume 67, Issue 1 (2018), 175-198.

Received: 12 September 2016
Revised: 3 November 2016
First available in Project Euclid: 20 February 2018

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Zentralblatt MATH identifier

Primary: 14T05: Tropical geometry [See also 12K10, 14M25, 14N10, 52B20] 14H51: Special divisors (gonality, Brill-Noether theory)


Atanasov, Stanislav; Ranganathan, Dhruv. A Note on Brill–Noether Existence for Graphs of Low Genus. Michigan Math. J. 67 (2018), no. 1, 175--198. doi:10.1307/mmj/1519095622.

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