{ "id": "0911.0126", "version": "v1", "published": "2009-11-01T04:33:06.000Z", "updated": "2009-11-01T04:33:06.000Z", "title": "On the Spectrum of Middle-Cubes", "authors": [ "Ke Qiu", "Rong Qiu", "Yong Jiang", "Jian Shen" ], "comment": "8 Pages", "categories": [ "math.CO" ], "abstract": "A middle-cube is an induced subgraph consisting of nodes at the middle two layers of a hypercube. The middle-cubes are related to the well-known Revolving Door (Middle Levels) conjecture. We study the middle-cube graph by completely characterizing its spectrum. Specifically, we first present a simple proof of its spectrum utilizing the fact that the graph is related to Johnson graphs which are distance-regular graphs and whose eigenvalues can be computed using the association schemes. We then give a second proof from a pure graph theory point of view without using its distance regular property and the technique of association schemes.", "revisions": [ { "version": "v1", "updated": "2009-11-01T04:33:06.000Z" } ], "analyses": { "subjects": [ "05C50" ], "keywords": [ "association schemes", "pure graph theory point", "distance regular property", "second proof", "middle levels" ], "note": { "typesetting": "TeX", "pages": 8, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2009arXiv0911.0126Q" } } }