Fractional total colourings of graphs of high girth
نویسندگان
چکیده
Reed conjectured that for every > 0 and ∆ there exists g such that the fractional total chromatic number of a graph with maximum degree ∆ and girth at least g is at most ∆ + 1 + . We prove the conjecture for ∆ = 3 and for even ∆ ≥ 4 in the following stronger form: For each of these values of ∆, there exists g such that the fractional total chromatic number of any graph with maximum degree ∆ and girth at least g is equal to ∆ + 1.
منابع مشابه
A note on n-tuple colourings and circular colourings of planar graphs with large odd girth
International Journal of Computer Mathematics Publication details, including instructions for authors and subscription information: http://www.informaworld.com/smpp/title~content=t713455451 A note on n-tuple colourings and circular colourings of planar graphs with large odd girth P. šparl ab; J. žerovnik ac a IMFM, Slovenia b FG, University of Maribor, Slovenia c FS, University of Maribor, Slov...
متن کاملTotal and fractional total colourings of circulant graphs
In this paper, the total chromatic number and fractional total chromatic number of circulant graphs are studied. For cubic circulant graphs we give upper bounds on the fractional total chromatic number and for 4-regular circulant graphs we find the total chromatic number for some cases and we give the exact value of the fractional total chromatic number in most cases.
متن کاملHomomorphism bounds and edge-colourings of K4-minor-free graphs
We present a necessary and sufficient condition for a graph of odd-girth 2k + 1 to bound the class of K4-minor-free graphs of odd-girth (at least) 2k + 1, that is, to admit a homomorphism from any such K4-minor-free graph. This yields a polynomial-time algorithm to recognize such bounds. Using this condition, we first prove that every K4-minor free graph of odd-girth 2k+1 admits a homomorphism ...
متن کاملFrugal Colouring of Graphs
A k-frugal colouring of a graph G is a proper colouring of the vertices of G such that no colour appears more than k times in the neighbourhood of a vertex. This type of colouring was introduced by Hind, Molloy and Reed in 1997. In this paper, we study the frugal chromatic number of planar graphs, planar graphs with large girth, and outerplanar graphs, and relate this parameter with several wel...
متن کاملRandomly Colouring Graphs with Girth Five and Large Maximum Degree
We prove that the Glauber dynamics on the k-colourings of a graph G on n vertices with girth 5 and maximum degree ∆ ≥ 1000 log n mixes rapidly if k = q∆ and q > β where β = 1.645... is the root of 2− (1− e−1/β)2 − 2βe−1/β = 0.
متن کاملذخیره 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 ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- J. Comb. Theory, Ser. B
دوره 101 شماره
صفحات -
تاریخ انتشار 2011