A metric graph satisfying w41=1$w_4^1 = 1$ that cannot be lifted to a curve satisfying dim⁡ (W41)=1$\dim \;(W_4^1 ) = 1$

Abstract

For all integers g ≥ 6 we prove the existence of a metric graph G with w41=1$w_4^1 = 1$ such that G has Clifford index 2 and there is no tropical modification G′ of G such that there exists a finite harmonic morphism of degree 2 from G′ to a metric graph of genus 1. Those examples show that not all dimension theorems on the space classifying special linear systems for curves have immediate translation to the theory of divisors on metric graphs.

Keywords

• metric graphs
• curves
• lifting problems
• special divisors
• clifford index
• dimension theorems
• 14h51
• 14t05
• 05c99