Homotopy groups of Hom complexes of graphs

نویسنده

  • Anton Dochtermann
چکیده

The notion of ×-homotopy from [Doca] is investigated in the context of the category of pointed graphs. The main result is a long exact sequence that relates the higher homotopy groups of the space Hom∗(G,H) with the homotopy groups of Hom∗(G,H ). Here Hom∗(G,H) is a space which parameterizes pointed graph maps from G to H (a pointed version of the usual Hom complex), and H is the graph of based paths in H. As a corollary it is shown that πi `

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Hom complexes and homotopy theory in the category of graphs

We investigate a notion of ×-homotopy of graph maps that is based on the internal hom associated to the categorical product in the category of graphs. It is shown that graph ×homotopy is characterized by the topological properties of the Hom complex, a functorial way to assign a poset (and hence topological space) to a pair of graphs; Hom complexes were introduced by Lovász and further studied ...

متن کامل

Hom complexes and homotopy in the category of graphs

We investigate a notion of ×-homotopy of graph maps that is based on the internal hom associated to the categorical product in the category of graphs. It is shown that graph ×homotopy is characterized by the topological properties of the Hom complex, a functorial way to assign a poset (and hence topological space) to a pair of graphs; Hom complexes were introduced by Lovász and further studied ...

متن کامل

Topology of Hom complexes and test graphs for bounding chromatic number

The Hom complex of homomorphisms between two graphs was originally introduced to provide topological lower bounds on the chromatic number of graphs. In this paper we introduce new methods for understanding the topology of Hom complexes, mostly in the context of Γ-actions on graphs and posets (for some group Γ). We view the Hom(T, •) and Hom(•, G) as functors from graphs to posets, and introduce...

متن کامل

ar X iv : m at h / 03 10 05 6 v 3 [ m at h . C O ] 2 6 A ug 2 00 4 COMPLEXES OF GRAPH HOMOMORPHISMS

Hom (G,H) is a polyhedral complex defined for any two undirected graphs G and H. This construction was introduced by Lovász to give lower bounds for chromatic numbers of graphs. In this paper we initiate the study of the topological properties of this class of complexes. We prove that Hom (Km,Kn) is homotopy equivalent to a wedge of (n−m)dimensional spheres, and provide an enumeration formula f...

متن کامل

ar X iv : m at h / 03 10 05 6 v 2 [ m at h . C O ] 5 M ay 2 00 4 COMPLEXES OF GRAPH HOMOMORPHISMS

Hom (G,H) is a polyhedral complex defined for any two undirected graphs G and H. This construction was introduced by Lovász to give lower bounds for chromatic numbers of graphs. In this paper we initiate the study of the topological properties of this class of complexes. We show that Hom (K2, Kn) is a boundary complex of a polytope, on which the natural Z2-action on the first argument, induces ...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:
  • J. Comb. Theory, Ser. A

دوره 116  شماره 

صفحات  -

تاریخ انتشار 2009