English

Rainbow path and color degree in edge colored graphs

Discrete Mathematics 2013-12-19 v1 Combinatorics

Abstract

Let GG be an edge colored graph. A {\it}{rainbow path} in GG is a path in which all the edges are colored with distinct colors. Let dc(v)d^c(v) be the color degree of a vertex vv in GG, i.e. the number of distinct colors present on the edges incident on the vertex vv. Let tt be the maximum length of a rainbow path in GG. Chen and Li showed that if dckd^c \geq k, for every vertex vv of GG, then t3k5+1t \geq \left \lceil \frac{3 k}{5}\right \rceil + 1 (Long heterochromatic paths in edge-colored graphs, The Electronic Journal of Combinatorics 12 (2005), # R33, Pages:1-33.) Unfortunately, proof by Chen and Li is very long and comes to about 23 pages in the journal version. Chen and Li states in their paper that it was conjectured by Akira Saito, that t2k3t \ge \left \lceil \frac {2k} {3} \right \rceil. They also states in their paper that they believe tkct \ge k - c for some constant cc. In this note, we give a short proof to show that t3k5t \ge \left \lceil \frac{3 k}{5}\right \rceil, using an entirely different method. Our proof is only about 2 pages long. The draw-back is that our bound is less by 1, than the bound given by Chen and Li. We hope that the new approach adopted in this paper would eventually lead to the settlement of the conjectures by Saito and/or Chen and Li.

Keywords

Cite

@article{arxiv.1312.5067,
  title  = {Rainbow path and color degree in edge colored graphs},
  author = {Anita Das and P. Suresh and S. V. Subrahmanya},
  journal= {arXiv preprint arXiv:1312.5067},
  year   = {2013}
}

Comments

4 pages

R2 v1 2026-06-22T02:30:16.933Z