1,007 research outputs found
Functional Inequalities: New Perspectives and New Applications
This book is not meant to be another compendium of select inequalities, nor
does it claim to contain the latest or the slickest ways of proving them. This
project is rather an attempt at describing how most functional inequalities are
not merely the byproduct of ingenious guess work by a few wizards among us, but
are often manifestations of certain natural mathematical structures and
physical phenomena. Our main goal here is to show how this point of view leads
to "systematic" approaches for not just proving the most basic functional
inequalities, but also for understanding and improving them, and for devising
new ones - sometimes at will, and often on demand.Comment: 17 pages; contact Nassif Ghoussoub (nassif @ math.ubc.ca) for a
pre-publication pdf cop
Large solutions of elliptic systems of second order and applications to the biharmonic equation
In this work we study the nonnegative solutions of the elliptic system \Delta
u=|x|^{a}v^{\delta}, \Delta v=|x|^{b}u^{\mu} in the superlinear case \mu
\delta>1, which blow up near the boundary of a domain of R^{N}, or at one
isolated point. In the radial case we give the precise behavior of the large
solutions near the boundary in any dimension N. We also show the existence of
infinitely many solutions blowing up at 0. Furthermore, we show that there
exists a global positive solution in R^{N}\{0}, large at 0, and we describe its
behavior. We apply the results to the sign changing solutions of the biharmonic
equation \Delta^2 u=|x|^{b}|u|^{\mu}. Our results are based on a new dynamical
approach of the radial system by means of a quadratic system of order 4,
combined with nonradial upper estimates
On a diffusion model with absorption and production
We discuss the structure of radial solutions of some superlinear elliptic
equations which model diffusion phenomena when both absorption and production
are present. We focus our attention on solutions defined in R (regular) or in R
\ {0} (singular) which are infinitesimal at infinity, discussing also their
asymptotic behavior. The phenomena we find are present only if absorption and
production coexist, i.e., if the reaction term changes sign. Our results are
then generalized to include the case where Hardy potentials are considered
Multiple positive solutions to elliptic boundary blow-up problems
We prove the existence of multiple positive radial solutions to the
sign-indefinite elliptic boundary blow-up problem where is a function superlinear at zero and at infinity,
and are the positive/negative part, respectively, of a sign-changing
function and is a large parameter. In particular, we show how the
number of solutions is affected by the nodal behavior of the weight function
. The proof is based on a careful shooting-type argument for the equivalent
singular ODE problem. As a further application of this technique, the existence
of multiple positive radial homoclinic solutions to is also considered
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