Abstract
We introduce and study a variant of Ramsey numbers for edge-ordered graphs, that is, graphs with linearly ordered sets of edges. The edge-ordered Ramsey number R¯e(G) of an edge-ordered graph G is the minimum positive integer N such that there exists an edge-ordered complete graph KN on N vertices such that every 2-coloring of the edges of KN contains a monochromatic copy of G as an edge-ordered subgraph of KN. We prove that the edge-ordered Ramsey number R¯e(G) is finite for every edge-ordered graph G and we obtain better estimates for special classes of edge-ordered graphs. In particular, we prove R¯e(G)≤2O(n3logn) for every bipartite edge-ordered graph G on n vertices. We also introduce a natural class of edge-orderings, called lexicographic edge-orderings, for which we can prove much better upper bounds on the corresponding edge-ordered Ramsey numbers.
Original language | English |
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Article number | 103100 |
Journal | European Journal of Combinatorics |
Volume | 87 |
DOIs | |
State | Published - 1 Jun 2020 |
Externally published | Yes |
ASJC Scopus subject areas
- Discrete Mathematics and Combinatorics