Anul LI 2006

S T U D I A

UNIVERSITATIS BABEŞ-BOLYAI

MATHEMATICA

2

Redacţia: 400084 Cluj-Napoca, Str. M. Kogălniceanu nr. 1 Tel: 405300

SUMAR – CONTENTS – SOMMAIRE

M. Bogdan, A stability result of a parametrized minimum problem . . . . . . . . . . . . . . . . 3

S. Boutechebak and B. Merouani, Frictional contact problems with normal

compliance and Coulomb’s law for non linear elastic bodies . . .. . . . . . . . . . . . . . . . . 13

Maria Teresa Calapso, Filip Defever and Radu Roşca, Pfaffian transformations . . . . .29

Ioana Chiorean and Claudia Stan, Remarks on some recurrence relations in

life annuity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Peter Danchev, Criteria for unit groups in commutative group rings . . . . . . . . . . . . . . 43

Cristinel Mortici, Nonexistence of nontrivial periodic solutions for semilinear

wave equations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

Cristinel Mortici and Ingrid Oancea, A nonsmooth extension for

the Bernstein-Stancu operators and an application . . . . . . . . . . . . . . . . . . . . . . . . . . 69

Olaru Ion Marian, Functional-differential equations of mixed type, via weakly

Picard operators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .83

Natalia Roşca, A new Monte Carlo estimator for systems of linear equations . . . . . . . 97

Ioan A. Rus and Edith Egri, Boundary value problems for iterative

functional-differential equations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

A. Tehranchi and S. R. Kulkarni, Some integral operators defined on p-valent

function by using hypergeometric functions . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . 127

Book Reviews . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143