Title: Stable gonality of graphs

Abstract: Based on analogies between algebraic curves and graphs, 
a new multigraph parameter was defined, called stable gonality. 
The gonality of an algebraic curve is the minimal degree of a 
morphism to the projective line, the stable gonality of a graph 
is the minimal degree of a morphism to a tree. Stable gonality 
measures the complexity of a multigraph. We will see that it is 
NP-hard to compute the gonality of a graph in general, but deciding 
whether a graph has gonality two can be done in quasilinear time.