For accurate and efficient use of wind power, it is important to know the statistical characteristics, availability, diurnal variation, and prediction of wind speed. Prediction of wind power permits the scheduling of the connection or the disconnection of wind turbines to achieve optimal operating costs. In this paper, a simple and accurate method for predicting wind speed based on weather-sens...

As a natural generalization of graph coloring, Vince introduced the star chromatic number of a graph G and denoted it by χ∗(G). Later, Zhu called it circular chromatic number and denoted it by χc(G). Let χ(G) be the chromatic number of G. In this paper, it is shown that if the complement of G is non-hamiltonian, then χc(G)=χ(G). Denote by M(G) the Mycielski graph of G. Recursively define Mm(G)=...

Let G be a connected graph with odd girth 2k + 1. Then G is a (2k + 1)-angulated graph if every two vertices of G are joined by a path such that each edge of the path is in some (2k + 1)-cycle. We prove that if G is (2k+1)-angulated, and H is connected with odd girth at least 2k+3, then any retract R of the box (or Cartesian) product G2H is isomorphic to S2T where S is a retract of G and T is a...

As a natural generalization of chromatic number of a graph, the circular chromatic number of graphs (or the star chromatic number) was introduced by A.Vince in 1988. Let M (G) denote the tth iterated Mycielski graph of G. It was conjectured by Chang, Huang and Zhu(Discrete mathematics,205(1999), 23-37) that for all n ≥ t+2, χc(M (Kn)) = χ(M (Kn)) = n+ t. In 2004, D.D.F. Liu proved the conjectur...

In the early 1980s, Gyárfás introduced concept of χ -bound with id="M4"> -binding functions thereby extending notion perfectness. There are a number challenging conjectures about id="M5"> -bound. Let id="M6"> G , id="M7"> ω and id="M8...

In the early 1980s, Gyárfás introduced concept of χ -bound with id="M4"> -binding functions thereby extending notion perfectness. There are a number challenging conjectures about id="M5"> -bound. Let id="M6"> G , id="M7"> ω and id="M8...

One of the most intriguing developments of modern set theory is the investigation of two-player infinite games of perfect information. Of course, it is clear that applied game theory, as any other branch of mathematics, can be modeled in set theory. But we are talking about the converse: the use of infinite games as a tool to study fundamental set theoretic questions. When such infinite games a...

We prove the existence of a free group of rotations of rank 2 which acts on the rational unit sphere without non-trivial fixed points. Introduction. The purpose of this paper is to prove that the group SO3(Q) of all proper orthogonal 3 × 3 matrices with rational entries has a free subgroup F2 of rank 2 such that for all w ∈ F2 different from the identity and for all ~r ∈ S2 ∩Q3 we have w(~r ) 6...

Breirem, K. (1939). Tierernuhrung, 11, 487. Breirem, K. (1954). In Festschrift anlasslich des 100 jahrigen Bestehens der Landwirtschaftlichen Versuchsstation Leipzig-Mockern. Vol. 2. IOO Jahre Mockern. Die Bewertung des Futterstoffe und andere Probleme der Tierernuhrung, p. 91. [K. Nehring, editor.] Berlin : Deutscher Bauernverlag. James, A. T. & Martin, A. J. P. (1952). Biochem. J. 50, 679. Ke...

We prove that the coindex of the box complex B(H) of a graph H can be measured by the generalised Mycielski graphs which admit a homomorphism to it. As a consequence, we exhibit for every graph H a system of linear equations solvable in polynomial time, with the following properties: If the system has no solutions, then coind(B(H))+2 ≤ 3; if the system has solutions, then χ(H) ≥ 4. We generalis...