Anul XLVII 2002

S T U D I A

UNIVERSITATIS BABEŞ-BOLYAI

MATHEMATICA

3

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

SUMAR – CONTENTS – SOMMAIRE

M. Banaru, On Nearly-Cosymplectic Hypersurfaces in Nearly-Kahlerian

Manifolds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Daniel Breaz and Nicoleta Breaz, Two Integral Operators . . . . . . . . . . . . . . . . . . . . . . 13

Adriana Buică, Quasilinearization for the Forced Duffing Equation . . . . . . . . . . .. . . .21

Endre Buzogany, Ildiko Ilona Mezei and Viorica Varga, Two-Variable

Variational-Hemivariational Inequalities . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . .31

Cristian Chifu-Oros, Functionals which Satisfy a Maximum Principle . . . . . . . . . . . .. 43

Rodica Covaci, X-Maximal Subgroups in Finite π-Solvable Groups with

Respect to a Schunck Class X . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . 53

Iuliu Crivei, On Some -Pure Exact Sequences of Modules . . . . . . . . . . . . . . . . . . . . . . .63

Zoltan Finta, Quantitative Estimates for Some Linear and Positive

Operators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

Vasile Pop, Maximal Sets on a Hypersphere . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

Liana Ţopan, Critical Sets of 1-Dimensional Manifolds . . . . . . . . . .. . . . . . . . . . . . . . .91

Book Reviews . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .99