scholarly journals Hypoelliptic differential operators with generalized constant coefficients

1998 ◽  
Vol 41 (1) ◽  
pp. 47-60 ◽  
Author(s):  
M. Nedeljkov ◽  
S. Pilipović
Keyword(s):  
Small Parameter ◽  
Differential Operators ◽  
Sufficient Conditions ◽  
Generalized Functions ◽  
Necessary And Sufficient Conditions ◽  
Order Estimate ◽  
Colombeau Generalized Functions ◽  
Constant Coefficients ◽  
Necessary And Sufficient

The space of Colombeau generalized functions is used as a frame for the study of hypoellipticity of a family of differential operators whose coefficients depend on a small parameter ε.There are given necessary and sufficient conditions for the hypoellipticity of a family of differential operators with constant coefficients which depend on ε and behave like powers of ε as ε→0. The solutions of such family of equations should also satisfy the power order estimate with respect to ε.

Embedding theorems and the spectra of certain differential operators

1991 ◽  
Vol 434 (1892) ◽  
pp. 643-656 ◽  
Keyword(s):  
Differential Operators ◽  
Necessary Conditions ◽  
Sufficient Conditions ◽  
Necessary And Sufficient Conditions ◽  
Independent Interest ◽  
Embedding Theorems ◽  
Necessary And Sufficient

This paper is concerned with problems of the form n Ʃ k =0 (─1) k ( ρ 2 k y ( k ))( k ) = λ r 2 y on R , ry ∈ L 2 ( R ) and gives conditions on the coefficients sufficient to ensure that the spectrum is discrete; necessary conditions are also given. In certain circumstances, necessary and sufficient conditions for discreteness are given, thus extending the celebrated Molcanov criterion. These results follow from embedding theorems which have independent interest.

scholarly journals The Oscillation of a Class of the Fractional-Order Delay Differential Equations

2014 ◽  
Vol 2014 ◽  
pp. 1-7
Author(s):  
Qianli Lu ◽  
Feng Cen
Keyword(s):  
Differential Equations ◽  
Fractional Order ◽  
Delay Differential Equations ◽  
Sufficient Conditions ◽  
Necessary And Sufficient Conditions ◽  
Analysis Method ◽  
Constant Coefficients ◽  
Delay Differential ◽  
Necessary And Sufficient

Several oscillation results are proposed including necessary and sufficient conditions for the oscillation of fractional-order delay differential equations with constant coefficients, the sufficient or necessary and sufficient conditions for the oscillation of fractional-order delay differential equations by analysis method, and the sufficient or necessary and sufficient conditions for the oscillation of delay partial differential equation with three different boundary conditions. For this,α-exponential function which is a kind of functions that play the same role of the classical exponential functions of fractional-order derivatives is used.

scholarly journals Necessary and sufficient conditions for oscillation of first order neutral delay difference equations

2015 ◽  
Vol 3 (2) ◽  
pp. 61
Author(s):  
A. Murgesan ◽  
P. Sowmiya
Keyword(s):  
Difference Equation ◽  
Sufficient Conditions ◽  
Necessary And Sufficient Conditions ◽  
Delay Difference Equation ◽  
Neutral Delay ◽  
First Order ◽  
Constant Coefficients ◽  
Necessary And Sufficient ◽  
Delay Difference Equations ◽  
Delay Difference

<p>In this paper, we obtained some necessary and sufficient conditions for oscillation of all the solutions of the first order neutral delay difference equation with constant coefficients of the form <br />\begin{equation*} \quad \quad \quad \quad \Delta[x(n)-px(n-\tau)]+qx(n-\sigma)=0, \quad \quad n\geq n_0 \quad \quad \quad \quad \quad \quad {(*)} \end{equation*}<br />by constructing several suitable auxiliary functions. Some examples are also given to illustrate our results.</p>

ON THE RELATION BETWEEN MINIMIZERS OF A Γ-LIMIT ENERGY AND OPTIMAL LIFTING IN BV-SPACE

2007 ◽  
Vol 09 (04) ◽  
pp. 447-472
Author(s):  
RADU IGNAT ◽  
ARKADY POLIAKOVSKY
Keyword(s):  
Small Parameter ◽  
Sufficient Conditions ◽  
Energy Functional ◽  
Necessary And Sufficient Conditions ◽  
Positive Parameter ◽  
Necessary And Sufficient ◽  
Limit Energy

We study the minimizers of an energy functional which is obtained as the Γ-limit of a family of functionals depending on a small parameter ε > 0, associated with a function u ∈ BV(Ω, S1) and a positive parameter p. We find necessary and sufficient conditions on p and the dimension under which these minimizers coincide with the optimal liftings of u, for everyu ∈ BV(Ω, S1).

scholarly journals Relatively bounded and compact perturbations ofnth order differential operators

1998 ◽  
Vol 21 (1) ◽  
pp. 47-68 ◽  
Author(s):  
Terry G. Anderson
Keyword(s):  
Perturbation Theory ◽  
Differential Operators ◽  
Sufficient Conditions ◽  
Necessary And Sufficient Conditions ◽  
Interpolation Inequalities ◽  
Compact Perturbations ◽  
Necessary And Sufficient

A perturbation theory fornth order differential operators is developed. For certain classes of operatorsL, necessary and sufficient conditions are obtained for a perturbing operatorBto be relatively bounded or relatively compact with respect toL. These perturbation conditions involve explicit integral averages of the coefficients ofB. The proofs involve interpolation inequalities.

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