Proof of the Lovasz Conjecture

dc.creatorBabson, Eric
dc.creatorKozlov, Dmitry N.
dc.date2004-02-24
dc.date2005-07-18
dc.date.accessioned2026-07-07T06:27:07Z
dc.date.available2026-07-07T06:27:07Z
dc.descriptionTo any two graphs G and H one can associate a cell complex Hom(G,H) by taking all graph multihomorphisms from G to H as cells. In this paper we prove the Lovasz Conjecture which states that if Hom(C_{2r+1},G) is k-connected, then χ(G)\geq k+4, where r,k\in Z, r\geq 1, k\geq -1, and C_{2r+1} denotes the cycle with 2r+1 vertices. The proof requires analysis of the complexes Hom(C_{2r+1},K_n). For even n, the obstructions to graph colorings are provided by the presence of torsion in H^*(Hom(C_{2r+1},K_n);Z). For odd n, the obstructions are expressed as vanishing of certain powers of Stiefel-Whitney characteristic classes of Hom(C_{2r+1},K_n), where the latter are viewed as $\zz$-spaces with the involution induced by the reflection of C_{2r+1}.
dc.descriptionRevised and updated version
dc.identifierhttps://arxiv.org/abs/math/0402395
dc.identifierhttp://arxiv.org/abs/math/0402395
dc.identifierAnnals of Mathematics, submitted 2/2/2004, accepted 28/7/2005, http://www.math.princeton.edu/~annals/issues/2005/AnnalsAcceptedPapers2005.pdf
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/97324
dc.subjectCombinatorics
dc.subjectAlgebraic Topology
dc.subject05C15; 57M15
dc.titleProof of the Lovasz Conjecture
dc.typetext

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