The Tropical Crossing Number of A Finite Graph
摘要
In 2015, Cartwright (2016) showed that any 3-regular metric graph arises as the skeleton of a tropical plane curve with nodes allowed. They introduced the tropical crossing number of a metric graph as the minimum number of nodes required for that graph with the prescribed lengths. We introduce the tropical crossing number of a finite, non-metric graph, the minimum number of nodes required to achieve that graph with any lengths on its edges. We prove that tropical crossing numbers can be arbitrary, even with prescribed crossing numbers. More precisely, for any integers