✦ LIBER ✦
Not Every Uniform Tree Covers Ramanujan Graphs
✍ Scribed by Alexander Lubotzky; Tatiana Nagnibeda
- Publisher
- Elsevier Science
- Year
- 1998
- Tongue
- English
- Weight
- 297 KB
- Volume
- 74
- Category
- Article
- ISSN
- 0095-8956
No coin nor oath required. For personal study only.
✦ Synopsis
The notion of Ramanujan graph has been extended to not necessarily regular graphs by Y. Greenberg. We construct infinite trees with infinitely many finite quotients, none of which is Ramanujan. We give a sufficient condition for a finite graph to be covered by such a tree.