Abstract
We prove that in the moduli space of genus-g metric graphs the locus of graphs with gonality at most d has the classical dimension min{3g−3,2g+2d−5}. This follows from a careful parameter count to establish the upper bound and a construction of sufficiently many graphs with gonality at most d to establish the lower bound. Here, gonality is the minimal degree of a non-degenerate harmonic map to a tree that satisfies the Riemann–Hurwitz condition everywhere. Along the way, we establish a convenient combinatorial datum capturing such harmonic maps to trees.
Original language | English |
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Pages (from-to) | 1-21 |
Number of pages | 21 |
Journal | Journal of Combinatorial Theory, Series A |
Volume | 156 |
DOIs | |
Publication status | Published - 1 May 2018 |
Keywords
- Brill–Noether theory
- Gonality
- Metric graphs
- Tropical geometry