Convex universal fixers

نویسندگان

  • Magdalena Lemanska
  • Rita Zuazua
چکیده

In [1] Burger and Mynhardt introduced the idea of universal fixers. Let G = (V,E) be a graph with n vertices and G a copy of G. For a bijective function π : V (G) → V (G), define the prism πG of G as follows: V (πG) = V (G)∪ V (G) and E(πG) = E(G)∪E(G′)∪Mπ, where Mπ = {uπ(u) | u ∈ V (G)}. Let γ(G) be the domination number of G. If γ(πG) = γ(G) for any bijective function π, then G is called a universal fixer. In [9] it is conjectured that the only universal fixers are the edgeless graphs Kn. In this work we generalize the concept of universal fixers to the convex universal fixers. In the second section we give a characterization for convex universal fixers (Theorem 6) and finally, we give an in infinite family of convex universal fixers for an arbitrary natural number n ≥ 10.

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

Interactions among nitrogen fixation and soil phosphorus acquisition strategies in lowland tropical rain forests.

Paradoxically, symbiotic dinitrogen (N2 ) fixers are abundant in nitrogen (N)-rich, phosphorus (P)-poor lowland tropical rain forests. One hypothesis to explain this pattern states that N2 fixers have an advantage in acquiring soil P by producing more N-rich enzymes (phosphatases) that mineralise organic P than non-N2 fixers. We assessed soil and root phosphatase activity between fixers and non...

متن کامل

Demography of Symbiotic Nitrogen-Fixing Trees Explains Their Rarity and Successional Decline in Temperate Forests in the United States

Symbiotic nitrogen (N) fixation is the major N input to many ecosystems. Although temperate forests are commonly N limited, symbiotic N-fixing trees ("N fixers") are rare and decline in abundance as succession proceeds-a challenging paradox that remains unexplained. Understanding demographic processes that underlie N fixers' rarity and successional decline would provide a proximate answer to th...

متن کامل

Spatio-temporal control of mutualism in legumes helps spread symbiotic nitrogen fixation

Mutualism is of fundamental importance in ecosystems. Which factors help to keep the relationship mutually beneficial and evolutionarily successful is a central question. We addressed this issue for one of the most significant mutualistic interactions on Earth, which associates plants of the leguminosae family and hundreds of nitrogen (N2)-fixing bacterial species. Here we analyze the spatio-te...

متن کامل

Positively Convex Modules and Ordered Normed Linear Spaces

A positively convex module is a non-empty set closed under positively convex combinations but not necessarily a subset of a linear space. Positively convex modules are a natural generalization of positively convex subsets of linear spaces. Any positively convex module has a canonical semimetric and there is a universal positively affine mapping into a regularly ordered normed linear space and a...

متن کامل

Nutrient acquisition, soil phosphorus partitioning and competition among trees in a lowland tropical rain forest.

We hypothesized that dinitrogen (N2 )- and non-N2 -fixing tropical trees would have distinct phosphorus (P) acquisition strategies allowing them to exploit different P sources, reducing competition. We measured root phosphatase activity and arbuscular mycorrhizal (AM) colonization among two N2 - and two non-N2 -fixing seedlings, and grew them alone and in competition with different inorganic an...

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:
  • Discussiones Mathematicae Graph Theory

دوره 32  شماره 

صفحات  -

تاریخ انتشار 2012