BEST PROXIMITY POINT THEOREMS FOR SINGLE- AND SET-VALUED NON-SELF MAPPINGS

We study the existence of best proximity points for single-valued non-self map-pings. Also, we prove a best proximity point theorem for set-valued non-self mappings in metric spaces with an appropriate geometric property. Examples are given to support the usability of our results.     

Ordered semigroups having the <Emphasis Type="Italic">P</Emphasis>-property

In this paper we obtain the following main results. The ordered semigroups which have the P-property are decomposable into archimedean semigroups. Moreover, they are decomposable into semigroupswith the P-property. Conversely, if an ordered semigroup S is a complete semilattice of semigroups which have the P-property, then S itself also has the P-property. An ordered semigroup is CS-indecomposable and has the P-property if and only if it is archimedean. If S is an ordered semigroup, then the relation N:= {(a, b) | N(a) = N(b)} (here N(a) is a filter of S generated by a (a ∈ S)) is the least complete semilattice congruence on S and the class (a) _N is a CS-indecomposable subsemigroup of S for each a ∈ S. We introduce the notion of the P _m -property and describe it in terms of the P-property. Our approach simplifies the proofs of the corresponding results about unordered semigroups. The text was submitted by the authors in English.     

再论Γ-环由元素性质确定的根

本文在 Γ-环中继续研究由元素性质确定的根性质 .首先证明了文献 [1]中主要定理的逆定理 , 从而使满足某些条件的元素所具有的性质 P与根性质 R可互相确定 .进而讨论确定的唯一性问题.利用 这些结果可得出 Γ-环的 Baer根是由元素的 m-幂零性所确定的根.     

On semidefinite linear complementarity problems

Given a linear transformation L:? ⁿ →? ⁿ and a matrix Q∈? ⁿ , where ? ⁿ is the space of all symmetric real n×n matrices, we consider the semidefinite linear complementarity problem SDLCP(L,? ⁿ ₊,Q) over the cone ? ⁿ ₊ of symmetric n×n positive semidefinite matrices. For such problems, we introduce the P-property and its variants, Q- and GUS-properties. For a matrix A∈R ^n×n , we consider the linear transformation L _A :? ⁿ →? ⁿ defined by L _A (X):=AX+XA ^T and show that the P- and Q-properties for L _A are equivalent to A being positive stable, i.e., real parts of eigenvalues of A are positive. As a special case of this equivalence, we deduce a theorem of Lyapunov. Received: March 1999 / Accepted: November 1999?Published online April 20, 2000     

Common Fixed Point Theorems and Q-prop erty for Quasi-contractive Mappings under c-distance on TVS-valued Cone Metric Spaces without the Normality

Fixed point and common fixed point results for mappings satisfying quasi-contractive conditions expressed in the terms of c-distance on TVS-valued cone met-ric spaces (without the underlying cone which is not normal) are obtained, and P-property and Q-property for mappings in the terms of c-distance are discussed. Our results generalize and improve many known results.     

The profile of the Cartesian product of graphs

Given a graph G, a proper labelingf of G is a one-to-one function from V(G) onto {1,2,…,|V(G)|}. For a proper labeling f of G, the profile widthw_f(v) of a vertex v is the minimum value of f(v)−f(x), where x belongs to the closed neighborhood of v. The profile of a proper labelingfofG, denoted by P_f(G), is the sum of all the w_f(v), where v∈V(G). The profile ofG is the minimum value of P_f(G), where f runs over all proper labeling of G. In this paper, we show that if the vertices of a graph G can be ordered to satisfy a special neighborhood property, then so can the graph G×Q_n. This can be used to determine the profile of Q_n and K_m×Q_n.     

Best proximity point theorems for single- and set-valued non-self mappings

We study the existence of best proximity points for single-valued non-self mappings. Also, we prove a best proximity point theorem for set-valued non-self mappings in metric spaces with an appropriate geometric property. Examples are given to support the usability of our results.     

再论Γ-环由元素性质确定的根

本文在Γ -环中继续研究由元素性质确定的根性质 .首先证明了文献 [1 ]中主要定理的逆定理 ,从而使满足某些条件的元素所具有的性质 P与根性质 R可互相确定 .进而讨论确定的唯一性问题 .利用这些结果可得出Γ -环的 Baer根是由元素的 m-幂零性所确定的根 .