A New Upper Bound on the Chromatic Number of Graphs with No Odd Kt Minor

نویسندگان

چکیده

Gerards and Seymour conjectured that every graph with no odd Kt minor is (t − 1)-colorable. This a strengthening of the famous Hadwiger’s Conjecture. Geelen et al. proved $$O(t\sqrt {\log t} )$$ -colorable. Using methods present authors Postle recently developed for coloring graphs minor, we make first improvement on this bound by showing O(t(logt)β)-colorable β > 1/4.

برای دانلود باید عضویت طلایی داشته باشید

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

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

A new upper bound on the cyclic chromatic number

A cyclic coloring of a plane graph is a vertex coloring such that vertices incident with the same face have distinct colors. The minimum number of colors in a cyclic coloring of a graph is its cyclic chromatic number χc . Let ∗ be themaximum face degree of a graph. There exist plane graphs with χc = 2 ∗ . Ore and Plummer [5] proved that χc ≤ 2 ∗, which bound was improved to 5 ∗ by Borodin, Sand...

متن کامل

List-chromatic Number and the Chromatic Number in Minor-closed and Odd-minor-closed Classes of Graphs

It is well-known (Feige and Kilian [24], H̊astad [39]) that approximating the chromatic number within a factor of n1−ε cannot be done in polynomial time for ε > 0, unless coRP = NP. Computing the list-chromatic number is much harder than determining the chromatic number. It is known that the problem of deciding if the list-chromatic number is k, where k ≥ 3, is Πp2-complete [37]. In this paper, ...

متن کامل

An upper bound for the chromatic number of line graphs

It was conjectured by Reed [12] that for any graph G, the graph’s chromatic number χ(G) is bounded above by l ∆(G)+1+ω(G) 2 m , where ∆(G) and ω(G) are the maximum degree and clique number of G, respectively. In this paper we prove that this bound holds if G is the line graph of a multigraph. The proof yields a polynomial time algorithm that takes a line graph G and produces a colouring that ac...

متن کامل

New results on upper domatic number of graphs

For a graph $G = (V, E)$, a partition $pi = {V_1,$ $V_2,$ $ldots,$ $V_k}$ of the vertex set $V$ is an textit{upper domatic partition} if $V_i$ dominates $V_j$ or $V_j$ dominates $V_i$ or both for every $V_i, V_j in pi$, whenever $i neq j$. The textit{upper domatic number} $D(G)$ is the maximum order of an upper domatic partition. We study the properties of upper domatic number and propose an up...

متن کامل

The locating-chromatic number for Halin graphs

Let G be a connected graph. Let f be a proper k -coloring of G and Π = (R_1, R_2, . . . , R_k) bean ordered partition of V (G) into color classes. For any vertex v of G, define the color code c_Π(v) of v with respect to Π to be a k -tuple (d(v, R_1), d(v, R_2), . . . , d(v, R_k)), where d(v, R_i) is the min{d(v, x)|x ∈ R_i}. If distinct vertices have distinct color codes, then we call f a locat...

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

ژورنال

عنوان ژورنال: Combinatorica

سال: 2021

ISSN: ['0209-9683', '1439-6912']

DOI: https://doi.org/10.1007/s00493-021-4390-3