| On almost-periodical solutions of an equation | 1$-$4 |
Abstract
Sufficient conditions are considered for existance of almost- periodical solutions of differential equation $\frac{dy}{dx}=p(x)y+q(x)$, where functions $p(x)$, $q(x)$ are $Sp$-almost periodical solutions in the sense of Stepanoff. A numerical-analytical algorithm of constructing almost- periodical solutions of such equations is proposed.
Keywords: Almost-periodical solutin
MSC: 34C27
| Some theorems on common fixed points | 5$-$9 |
Abstract
Three general theorems on common fixed points of non-commuting selfmaps of a metric space are given. These results generalize the recent results of Naidu and Prasad [7], Leader [5] and a number of earlier results.
Keywords: Common fixed points, non-commuting selfmaps.
MSC: 54H25
| Methode von Euler-schen typus zum Näherungsweisen Auflosen einer areolaren Differentialgleichung | 11$-$15 |
Abstract
Es sei eine areoläre Differentialgleichung $$ Dw=F(z,\bar z,w)\tag1 $$ mit der Anfangsbedingung $$ \a_{a/z}w=w_0(z)\tag2 $$ gegeben, wobei $w_0(z)$ eine gegebene analytische Funktion ist, und $$ Dw=(u'_x-v'_y)+i(u'_y+v'_x)=2w'_{\bar z} $$ den bekannten Differentialoperator von Kolossov darstellt. In dieser Arbeit löst man die Gleichung (1) mit der Anfangsbedingung (2) durch eine Näherungsmethode vom Euler-schen Typus.
Keywords: Areolar equation
MSC: 34A20
| Extremal disconnectedness in fuzzy topological spaces | 17$-$23 |
Abstract
The notion of extremal disconnectedness is introduced for fuzzy topological spaces. Various properties of this notion are discussed. Interrelationship of some weaker forms of fuzzy continuity is studied in the light of extremal diconnectedness.
Keywords: Fuzzy points, neighbourhood, quasi-neighbourhood, quasi-coincident fuzzy sets, fuzzy continuity
MSC: 54A40
| Nearly $pT_i$-continuous mappings | 25$-$28 |
Abstract
Some generalizations of $T_i$-pairwise continuous functions and similar generalizations of pairwise $T_i$-spaces, for $i=1$, 2,~3 are introduced and their relationship with the concept of $T_i$-pairwise continuity is studied.
Keywords: Nearly $PT_i$-spaces, $PT(i,k)$-spaces, nearly $pT_i$-continuous mappings
MSC: 54E55
| A note on inequalities of Diaz-Matcalf type for isotonic linear functionals | 29$-$31 |
Abstract
Some refinements of the Beaseck-Pečarić generalization of the Diaz-Metcalf inequality are proved.
Keywords: Diaz-Metcalf-type inequalities, isotonic linear fucntionals
MSC: 26D20
| L'équation non-homog\`ene de Vécua | 33$-$39 |
Abstract
Le m\`ethode de Lagrange de la variation des constantes au cas des équations aréolaires avec une conjugaison de la fonction inconnue $\bar w$, o\`u appartient l'équation bien connue de I. N. Vecua [1], n'étant pas valable, on la remplace dans cet article par un m\`ethode des itérations qui est plus immédiat et plus abordable aux traitements numériques.
Keywords: Vécua equation
MSC: 34A20
| Determinantal representations of weighted Moore-Penrose inverse | 41$-$50 |
Abstract
In this paper we introduce determinantal representation of {\it weighted Moore-Penrose inverse\/} of a rectangular matrix. We generalize concept of generalized algebraic complement, introduced by Moore, Arghiriade, Dragomir and Gabriel. This extension is denoted as weighted generalized algebraic complement. Moreover, we derive an explicit determinantal representation for the weighted least-squares minimum norm solution of a linear system and prove that this solution lies in the convex hull of the solutions to the square subsystems of the original system.
Keywords: Weighted Moore-Penrose inverse, generlaized algebraic complement, determinantal representation.
MSC: 15A09, 15A60, 65F35
| Remark on some abstract distance spaces | 51$-$56 |
Abstract
Some terminological questions are discussed in connection with two essentially different classes of abstract distance spaces.
Keywords: Abstract distance spaces
MSC: 54A99
| Djuro R. Kurepa | 57$-$61 |