The fractional chromatic number, the Hall ratio, and the lexicographic product
نویسندگان
چکیده
منابع مشابه
On the fractional chromatic number and the lexicographic product of graphs
For graphs G and H let GH] be their lexicographic product and let f (G) = inff(GK n ])=n j n = 1; 2; : : :g be the fractional chromatic number of G. For n 1 set G n = fG j (GK n ]) = nn(G)g. Then lim n!1 G n = fG j f (G) = (G)g: Moreover, we prove that for any n 2 the class G n forms a proper subclass of G n?1. As a by-product we show that if G is a-extremal, vertex transitive graph on (G)(G) ?...
متن کاملOn the ultimate lexicographic Hall-ratio
The Hall-ratio ρ(G) of a graph G is the ratio of the number of vertices and the independence number maximized over all subgraphs of G. The ultimate lexicographic Hall-ratio of a graph G is defined as limn→∞ n √ ρ(G◦n), where G◦n denotes the nth lexicographic power of G (that is, n times repeated substitution of G into itself). Here we prove the conjecture of Simonyi stating that the ultimate le...
متن کاملOn the chromatic number of the lexicographic product and the Cartesian sum of graphs
Let G[H] be the lexicographic product of graphs G and H and let G⊕H be their Cartesian sum. It is proved that if G is a nonbipartite graph, then for any graph H, χ(G[H]) ≥ 2χ(H)+d k e, where 2k+1 is the length of a shortest odd cycle of G. Chromatic numbers of the Cartesian sum of graphs are also considered. It is shown in particular that for χ–critical and not complete graphs G and H, χ(G ⊕ H)...
متن کاملthe analysis of the role of the speech acts theory in translating and dubbing hollywood films
از محوری ترین اثراتی که یک فیلم سینمایی ایجاد می کند دیالوگ هایی است که هنرپیش گان فیلم میگویند. به زعم یک فیلم ساز, یک شیوه متأثر نمودن مخاطب از اثر منظوره نیروی گفتارهای گوینده, مثل نیروی عاطفی, ترس آور, غم انگیز, هیجان انگیز و غیره, است. این مطالعه به بررسی این مسأله مبادرت کرده است که آیا نیروی فراگفتاری هنرپیش گان به مثابه ی اعمال گفتاری در پنج فیلم هالیوودی در نسخه های دوبله شده باز تولید...
15 صفحه اولImproved Bounds for the Chromatic Number of the Lexicographic Product of Graphs
An upper bound for the chromatic number of the lexicographic product of graphs which unifies and generalizes several known results is proved. It is applied in particular to characterize graphs that have a complete core. An improved lower bound is also given.
متن کاملذخیره 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: Discrete Mathematics
سال: 2009
ISSN: 0012-365X
DOI: 10.1016/j.disc.2008.05.049