Acta Mathematica Vietnamica

Acta Mathematica Vietnamica

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Issue 2, Volume 18, December 1993

1993 · Open access

  1. A SUFFICIENT CONDITION FOR BIJECTIVITY OF POLYNOMIAL MAPS ON THE REAL PLANE NGUYEN VAN CHAU PDF
    ▸ Abstract

    It is shown that the non-singular polynomial map $f$ of $R^2$ into itself is a global diffeomorphism of $R^2$ if $0\not\in Co\{Df(x)v\| \|x\| > Const.\}$ for a vector $v$. This result is a variant of a theorem of Olech and Meister [3, 6] for the polynomial case.

    215-218
  2. A NEW INTEGRAL CONTAINING THE JACOBI POLYNOMIAL S. D. BAJPAI PDF
    ▸ Abstract

    A new integral containing the Jacobi polynomials is given with an elementary multiplier function.

    219-223
  3. ON THE ROCKAFELLAR DERIVATIVE OF MARGINAL FUNCTIONS AND APPLICATIONS DO VAN LUU PDF
    ▸ Abstract

    In this paper, some evaluations of the directional Rockafellar derivative of a function defined by $\varphi_F(x)=\mathrm{inf}\{f(x,y)\,|\, y\in F(x)\}$ via the directional Clarke and Rockafellar derivative of $f$ are shown. These evaluations are applied to find necessary optimality conditions for generalized optimal control problems governed by hemivariational inequalities.

    225-236
  4. A SUBCLASSIFICATION OF UNIMODAL DISTRIBUTIONS NGUYEN VAN THU PDF
    ▸ Abstract

    We introduce and study classes $\mathcal P_{\alpha}$,  $\alpha > 0$, of $\alpha$-times unimodal distributions. Various characterizations of these distributions are obtained and relations between them and fractional calculus are established.

    237-249
  5. MODULAR INVARIANTS AND THE mod $p$ COHOMOLOGY ALGEBRA OF THE INFINITE SYMMETRIC GROUP NGUYEN HUU VIET HUNG PDF
    ▸ Abstract

    We determine the mod $p$ cohomology algebra of the infinite symmetric group for $p$ an odd prime by using what we call the Dickson characteristic classes. These classes are constructed by means of the Dickson-Mùi invariants of $GL(n,\mathbb Z_p)$ on the algebra $E(x_1,\dots,x_n)\otimes \mathbb Z_p[y_1,\dots,y_n]$. They are closely related to the classical Chern classes.

    265-294
  6. AN IMPROVEMENT FOR PARALLEL-ITERATED RUNGE-KUTTA-NYSTRÖM METHODS NGUYEN HUU CONG PDF
    ▸ Abstract

    This paper deals with predictor-corrector (PC) iteration of Runge-Kutta-Nyström (RKN) methods for integrating initial-value problems for special second-order, ordinary differential equations. We consider RKN correctors based on direct collocation techniques with high stage-order so that the stage-values can be used by extrapolation techniques to construct high-order predictior methods with no additional sequential right-hand side evaluations and without increasing number of processors. Having the high-order predictor in addition with the small convergence factor and error constant, the parallel-iterated PC methods based on direct collocation RKN correctors considered in this paper show the improved efficiency when they are compared to the PIRKN methods available in the literature.

    295-307