Chip-firing based methods in the Riemann–Roch theory of directed graphs

Autor: Lilla Tóthmérész, Bálint Hujter
Rok vydání: 2019
Předmět:
Zdroj: European Journal of Combinatorics. 78:90-104
ISSN: 0195-6698
DOI: 10.1016/j.ejc.2019.01.007
Popis: Baker and Norine proved a Riemann--Roch theorem for divisors on undirected graphs. The notions of graph divisor theory are in duality with the notions of the chip-firing game of Bj\"orner, Lov\'asz and Shor. We use this connection to prove Riemann--Roch-type results on directed graphs. We give a simple proof for a Riemann--Roch inequality on Eulerian directed graphs, improving a result of Amini and Manjunath. We also study possibilities and impossibilities of Riemann--Roch-type equalities in strongly connected digraphs and give examples. We intend to make the connections of this theory to graph theoretic notions more explicit via using the chip-firing framework.
Comment: 22 pages, 4 figures
Databáze: OpenAIRE