Ugo Gianazza's List of Papers
[80] U. Gianazza and D. Jesus - Boundary Estimates for Doubly Nonlinear Parabolic Equations - Nonlinear Differ. Equ. Appl. 32, 17 (2025), 1-42. See also this other link
Abstract:
We consider non-negative, weak solutions to the doubly nonlinear parabolic equation
\[
\partial_t u^q-{\operatorname{div}}(|Du|^{p-2}Du)=0
\]
in the super-critical fast diffusion regime
$0\lt p-1\lt q\lt\frac{N(p-1)}{(N-p)_+}$. We show that when solutions vanish continuously at the Lipschitz boundary of a parabolic cylinder $\Omega_T$, they satisfy proper Carleson estimates. Assuming further regularity for the boundary of the domain $\Omega_T$, we obtain a power-like decay at the boundary and a boundary Harnack inequality.
[79] U. Gianazza and N. Liao - Continuity of the temperature in a multi-phase transition problem. Part II -
Interfaces and Free Boundaries, 26(4) (2024), 625-674.
Abstract:
Local continuity is established for locally bounded, weak solutions to a doubly nonlinear parabolic equation that models the temperature of a material undergoing a multi-phase transition. The enthalpy, as a maximal monotone graph of the temperature, is allowed to possess several jumps and/or infinite derivatives at the transition temperatures. The effect of the $p$-Laplacian type diffusion is also considered. As an application, we demonstrate a continuity result for the saturation in the flow of two immiscible fluids through a porous medium, when irreducible saturation is present.
[78] U. Gianazza and N. Liao - Continuity of the temperature in a multi-phase transition problem. Part III - JAMA 150, (2023), 583-607.
Abstract:
We establish local continuity of locally bounded weak solutions to a doubly non-linear parabolic equation that models the temperature in multi-phase transitions. The enthalpy allows for general maximal monotone graphs of the temperature. Remarkably, moduli of continuity can be estimated without an explicit form of the enthalpy.
[77] U. Gianazza and J. Siljander - Local Bounds of the Gradient of Weak Solutions to the Porous Medium Equation - Partial Differ. Equ. Appl. 4, 8 (2023). See also this other link
Abstract:
Let $u$ be a nonnegative, local, weak solution to the porous medium equation
\[
\partial_t u-\Delta u^m=0
\]
for $m\ge2$ in a space-time cylinder $\Omega_T$. Fix a point
$(x_o,t_o)\in\Omega_T$: if the average
\[
a{\buildrel\mbox{def}\over{=}}\frac1{|B_r(x_o)|}\int_{B_r(x_o)}u(x,t_o)\,dx>0,
\]
then the quantity $|\nabla u^{m-1}|$ is locally bounded in a proper
cylinder, whose center lies at time $t_o+a^{1-m}r^2$. This implies that in the
same cylinder the solution $u$ is Hölder continuous with exponent
$\alpha=\frac1{m-1}$, which is known to be optimal. Moreover, $u$ presents a
sort of instantaneous regularisation, which we quantify.
[76] U. Gianazza - Carleson estimates for the singular parabolic
p-Laplacian in time-dependent domains - Rendiconti Lincei. Matematica ed Applicazioni 32, (2021), 669-690.
Abstract:
We deal with the parabolic $p$-Laplacian in the so-called singular
super-critical range $\frac{2N}{N+1}\lt p\lt 2$, and we prove Carleson
estimates for non-negative solutions in suitable non-cylindrical
domains $\Omega\subset{\mathbb R}^{N+1}$. The sets $\Omega$ satisfy a proper
NTA condition, tailored on the parabolic $p$-Laplacian. As an intermediate
step, we show that in these domains non-negative solutions which
vanish at the boundary, are Hölder continuous up to the same boundary.
[75] U. Gianazza - In memoriam Emmanuele DiBenedetto (1947-2021) - Advances in Calculus of Variations (2021), 1-18.
Abstract:
Emmanuele DiBenedetto passed away in May 2021, after battling cancer for fifteen months. I have had the unique privilege to collaborate and discuss Mathematics with him, almost up to his final days. Here I briefly present his life and those mathematical results of his, which I consider most familiar with.
[74] U. Gianazza and N. Liao - Continuity of the temperature in a multi-phase transition problem - Mathematische Annalen, 384, (2022), 211-245.
Abstract:
Locally bounded, local weak solutions to a doubly nonlinear parabolic equation, which models the multi-phase transition of a material, is shown to be locally continuous. Moreover, an explicit modulus of continuity is given. The effect of the $p$-Laplacian type diffusion is also considered.
[73] U. Gianazza and N. Liao - A Boundary Estimate for Singular Sub-Critical Parabolic Equations - Int. Math. Res. Notices 10, (2022), 7332-7353.
Abstract:
We prove an estimate on the modulus of continuity at a boundary point of a cylindrical domain for local weak solutions to singular parabolic equations of $p$-laplacian type, with $p$ in the sub-critical range $(1,\frac{2N}{N+1}]$. The estimate is given in terms of a Wiener-type integral, defined by a proper elliptic $p$-capacity.
[72] D. Andreucci and U. Gianazza - A Short Presentation of Emmanuele's Work - in V. Vespri et al., (eds.), Harnack Inequalities and Nonlinear Operators. Springer INdAM Series, vol 46. Springer, Cham. 2021.
Abstract: As the title suggests, this is a short presentation of DiBenedetto's mathematical work. In the first part Ugo Gianazza gives a general overview, without entering too much into details of specific papers; in his contribution Daniele Andreucci focuses on DiBenedetto's accomplishments in BioMathematics.
[71] U. Gianazza and S. Salsa - On the Harnack Inequality for Non-divergence Parabolic Equations - Mathematics in Engineering, 3(3) (2020), 1-11.
Abstract:
In this paper we propose an elementary proof of the Harnack inequality for linear parabolic equations in non-divergence form.
[70] U. Gianazza and C. Klaus - $p$-Parabolic Approximation of Total Variation Flow Solutions - Indiana Univ. Math. J., 68 No. 5 (2019), 1519-1550.
Abstract:
We show that variational solutions to the Cauchy-Dirichlet problem for the total variation flow can be built as the limit of variational solutions to the same problem for the parabolic $p$-Laplacian.
[69] F. Rossella, V. Bellani, M. Tommasini, U. Gianazza, E. Comini, C. Soldano - 3D Multi-Branched SnO2 Semiconductor Nanostructures as Optical Waveguides - Materials, (2019), 12, 3148, 1-9.
Abstract:
Nanostructures with complex geometry have gathered interest recently due to some
unusual and exotic properties associated with both their shape and material. 3D multi-branched SnO2 one-dimensional nanostructrures, characterized by a node - i.e., the location where two or more branches originate, are the ideal platform to distribute signals of different natures. In this work, we study how this particular geometrical configuration affects light propagation when a light source (i.e.,
laser) is focused onto it. Combining scanning electron microscopy (SEM) and optical analysis along with Raman and Rayleigh scattering upon illumination, we were able to understand, in more detail, the mechanism behind the light-coupling occurring at the node. Our experimental findings show that multi-branched semiconductor 1D structures have great potential as optically active nanostructures with waveguiding properties, thus paving the way for their application as novel building blocks for
optical communication networks
[68] U. Gianazza and S. Schwarzacher - Self-improving property of the fast diffusion equation - Journal of Functional Analysis, 1-57, (2019).
Abstract:
We show that the gradient of the $m$-power of a solution to a singular parabolic equation of porous medium-type (also known as fast diffusion equation), satisfies a reverse Hölder inequality in suitable intrinsic cylinders. Relying on an intrinsic Calderón-Zygmund covering argument, we are able to prove the local higher integrability of such a gradient for $m\in\left(\frac{(n-2)_+}{n+2},1\right)$. Our estimates are satisfied for a general class of growth assumptions on the non linearity. In this way, we extend the theory for $m\geq 1$ (see [5] in this list of references) to the singular case. In particular, an intrinsic metric that depends on the solution itself is introduced for the singular regime.
[67] U. Gianazza and N. Liao - A Boundary Estimate for Degenerate Parabolic Diffusion Equation - Potential Analysis, 53, (2020), 977-995. See also this other link
Abstract:
We prove an estimate on the modulus of continuity at a boundary point of a
cylindrical domain for local weak solutions to degenerate parabolic equations
of $p$-laplacian type. The estimate is given in terms of a Wiener-type
integral, defined by a proper elliptic $p$-capacity.
[66] U. Gianazza and S. Schwarzacher - Self-improving property of degenerate parabolic equations of porous medium-type - American Journal of Mathematics, 141(2), (2019), 399-446.
Abstract:
We show that the gradient of solutions to degenerate parabolic equations of porous medium-type satisfies a reverse Hölder inequality in suitable intrinsic cylinders. We modify the by-now classical Gehring lemma by introducing an intrinsic Calderón-Zygmund covering argument, and we are able to prove local higher integrability of the gradient of a proper power of the solution $u$.
[65] U. Gianazza, N. Liao and T. Lukkari - A Boundary Estimate for Singular Parabolic Diffusion Equations - Nonlinear Differential Equations and Applications, 25(4), (2018). See also this other link
as part of the Springer Nature SharedIt initiative
Abstract:
We prove an estimate on the modulus of continuity at a boundary point of a cylindrical domain for local weak solutions to singular parabolic equations of $p$-laplacian type. The estimate is given in terms of a Wiener-type integral, defined by a proper elliptic $p$-capacity.
[64] A. Björn, J. Björn, U. Gianazza and J. Siljander - Boundary regularity for the porous medium equation - Archive for Rational Mechanics and Analysis, 230(2), (2018), 493-538. See also this other link
as part of the Springer Nature SharedIt initiative.
Abstract:
We study the boundary regularity of solutions to the porous medium equation $u_t=\Delta u^m$ in the degenerate range $m>1$. In particular, we show that in cylinders the Dirichlet problem with positive continuous boundary data on the parabolic boundary has a solution which attains the boundary values, provided that the spatial domain satisfies the elliptic Wiener criterion. This condition is known to be optimal, and it is a consequence of our main theorem which establishes a barrier characterization of regular boundary points for general - not necessarily cylindrical - domains in $\mathbb R^{n+1}$. One of our fundamental tools is a new strict comparison principle between sub- and superparabolic functions, which makes it essential for us to study both nonstrict and strict Perron solutions to be able to develop a fruitful boundary regularity theory. Several other comparison principles and pasting lemmas are also obtained. In the process we obtain a rather complete picture of the relation between sub/superparabolic functions and weak sub/supersolutions.
[63] E. DiBenedetto, U. Gianazza and V.Vespri - Remarks on
Local Boundedness and Local Höolder Continuity of Local Weak
Solutions to Anisotropic $p$-Laplacian Type Equations - J.
Elliptic Parabol. Equ., 2, (2016), 157-169. The paper can also be
found at this other link.
Abstract: Locally bounded, local weak solutions to a
special class of quasilinear, anisotropic, $p$-Laplacian type
elliptic equations, are shown to be locally Hölder continuous.
Homogeneous local upper bounds are established for local weak
solutions to a general class of quasilinear anisotropic equations.
[62] U. Gianazza and S. Salsa - On the Boundary Behaviour of
Solutions to Parabolic Equations of $p-$Laplacian Type - Rend.
Istit. Mat. Univ. Trieste, 48, (2016), 463-483.
Abstract:
This is a survey, in which we describe some recent results on the
boundary behavior of non-negative solutions to a class of
degenerate/singular parabolic equations, whose prototype is the
parabolic $p$-Laplacian. More precisely we focus on Carleson-type
estimates and boundary Harnack principles.
[61] V. Bögelein, F. Duzaar and U. Gianazza - Sharp
boundedness and continuity results for the singular porous medium
equation - Israel
Journal of Mathematics, 214, (2016), 259-314. See also this other
link as part of the Springer Nature
SharedIt initiative.
Abstract: We consider
non-homogeneous, singular ($m\in(0,1)$) parabolic equations of porous
medium type of the form $$ u_t-\operatorname{div} \mathbf
A(x,t,u,Du)=\mu\qquad\mbox{in $E_T$,} $$ where $E_T$ is a space time
cylinder, and $\mu$ is a Radon-measure having finite total mass
$\mu(E_T)$. In the range $m\in(\frac{(N-2)_+}{N},1)$ we establish
sufficient conditions for the boundedness and the continuity of $u$
in terms of a natural Riesz potential of the right-hand side measure
$\mu$.
[60] E. DiBenedetto and U. Gianazza - Some Properties of
DeGiorgi Classes - Rend.
Istit. Mat. Univ. Trieste, 48, (2016), 245-260.
Abstract:
The DeGiorgi classes $[DG]_p(E;\gamma)$, defined in (1.1)$_\pm$ of
the manuscript encompass, solutions of quasilinear elliptic equations
with measurable coefficients as well as minima and $Q$-minima of
variational integrals. For these classes we present some new results
(§ 2 and § 3.1), and some known facts scattered in the
literature (§ 3-§ 5), and formulate some open issues (§
6).
[59] A. Björn, J. Björn and U. Gianazza - The
Petrovskiĭ criterion and barriers for degenerate and singular
p-parabolic equations - Math.
Ann., 368, (2017), 885-904. See also this other link
as part of the Springer Nature SharedIt initiative.
Abstract:
In this paper we obtain sharp Petrovskiĭ criteria for the
$p$-parabolic equation, both in the degenerate case $p$>2 and the
singular case 1<$p$<2. We also give an example of an irregular
boundary point at which there is a barrier, thus showing that
regularity cannot be characterized by the existence of just one
barrier.
[58] F.G. Düzgün, U. Gianazza and V. Vespri -
1-Dimensional Harnack Estimates - Discrete
and Continuous Dynamical Systems, Series S, 9(3), (2016), 675-685.
Abstract: Let $u$ be a non-negative super-solution to a
1-dimensional singular parabolic equation of $p$-Laplacian type,
$p\in(1,2)$. If $u$ is bounded below on a time-segment
$\{y\}\times(0,T]$ by a positive number $M$, then it has a power-like
decay of order $\frac p{2-p}$ with respect to the space variable $x$
in ${\mathbb R}\times[T/2,T]$. This fact, stated quantitatively in
Proposition 1.1, is a sidewise spreading of positivity of solutions
to such singular equations, and can be considered as a form of
Harnack inequality. The proof of such an effect is based on
geometrical ideas.
[57] B. Avelin, U. Gianazza and S. Salsa - Boundary Estimates
for Certain Degenerate and Singular Parabolic Equations - J.
Eur. Math. Soc. 18, (2016), 381-424.
Abstract: We
study the boundary behavior of non-negative solutions to a class of
degenerate/singular parabolic equations, whose prototype is the
parabolic $p$-Laplacian. Assuming that such solutions continuously
vanish on some distinguished part of the lateral part $S_T$ of a
Lipschitz cylinder, we prove Carleson-type estimates, and deduce some
consequences under additional assumptions on the equation or the
domain. We then prove analogous estimates for non-negative solutions
to a class of degenerate/singular parabolic equations, of porous
medium type.
[56] E. DiBenedetto, U. Gianazza and C. Klaus - A Necessary and
Sufficient Condition for the Continuity of Local Minima of Parabolic
Variational Integrals with Linear Growth - Adv.
Calc. Var. 10(3), (2017), 209-221.
Abstract: For
proper minimizers of parabolic variational integrals with linear
growth with respect to $|Du|$, we establish a necessary and
sufficient condition for $u$ to be continuous at a point $(x_o,t_o)$,
in terms of a sufficient fast decay of the total variation of $u$
about $(x_o,t_o)$. These minimizers arise also as proper solutions to
the parabolic $1$-Laplacian equation. Hence, the continuity condition
continues to hold for such solutions.
[55] E. DiBenedetto and U. Gianazza - A Wiener-Type Condition
for Boundary Continuity of Quasi-Minima of Variational Integrals
- manuscripta
math. 149, (2016), 339-346. Unfortunately, the online version
does not take into account all the corrections the authors asked for
in the galley proofs; interested readers can refer to preprint.
Abstract: A Wiener-type condition for the continuity at
the boundary points of Q-minima, is established, in terms of the
divergence of a suitable Wiener integral.
[54] V. Bögelein, F. Duzaar and U. Gianazza - Very weak
solutions of singular porous medium equations with measure data -
Communications on
Pure and Applied Analysis, 14(1), (2015), 23-49.
Abstract:
We consider non-homogeneous, singular ($m\in(0,1)$) porous medium
type equations with a non-negative Radon-measure $\mu$ having finite
total mass $\mu(E_T)$ on the right-hand side. We deal with a
Cauchy-Dirichlet problem for these type of equations, with
homogeneous boundary conditions on the parabolic boundary of the
domain $E_T$, and we establish the existence of\ a solution in the
sense of distributions. Finally, we show that the constructed
solution satisfies linear pointwise estimates via linear Riesz
potentials.
[53] U. Gianazza - Degenerate and Singular Porous Medium Type Equations
with Measure Data - in J. Escher et al., (eds.), Elliptic and Parabolic Equations, Springer Proc. Math. Stat., 119, (2015), 139--158.
Abstract: We consider the inhomogeneous porous medium equation
$$\partial_t u -\Delta u^m=\mu,\qquad m>\frac{(N-2)_+}{N},$$
and more general equations of porous medium type with a non-negative Radon measure $\mu$ on the right-hand side. In a first step, we prove a priori estimates for weak solutions in terms of a linear Riesz potential of the right-hand side measure, which takes exactly the same form as the one for the classical heat equation. Then, we give an optimal criterium for the continuity of weak solutions, again in terms of a Riesz potential. Finally, we prove the existence of non-negative very weak solutions, and show that these constructed very weak solutions satisfy the same estimates. We deal with both the degenerate case $m>1$, and the singular case $m\in(\frac{(N-2)_+}{N},1)$.
[52] V. Bögelein, F. Duzaar and U. Gianazza - Continuity
estimates for porous medium type equations with measure data -
Journal of
Functional Analysis, 267(9), (2014), 3351-3396.
Abstract:
We consider parabolic equations of porous medium type of the form $$
u_t-\operatorname{div} \mathbf A(x,t,u,Du)=\mu\qquad\mbox{in $E_T$,}
$$ in some space time cylinder $E_T$. The most prominent example
covered by our assumptions is the classical porous medium equation $$
u_t-\Delta u^m =\mu\qquad\mbox{in $E_T$,} $$ {with $m\ge1$.} We
establish a sufficient condition for the continuity of $u$ in terms
of a natural Riesz potential of the right-hand side measure $\mu$. As
an application we come up with a borderline condition ensuring the
continuity of $u$: more precisely, if $\mu\in
L\big(\frac{N+2}2,1\big)$, then $u$ is continuous in $E_T$.
[51] E. DiBenedetto, U. Gianazza and N. Liao - Two Remarks on
the Local Behavior of Solutions to Logarithmically Singular Diffusion
Equations and its Porous-Medium Type Approximations - Riv.
Mat. Univ. Parma, vol. 5(1), (2014), 139-182.
Abstract
For the logarithmically singular parabolic equation $$u_t-\Delta\ln
u=0,$$ we establish a Harnack type estimate in the $L^1_{loc}$
topology, and we show that the solutions are locally analytic in the
space variables and differentiable in time. The main assumption is
that $\ln u$ possesses a sufficiently high degree of integrability.
These two properties are known for solutions of singular porous
medium type equations ($m\in(0,1)$), which formally approximate the
logarithmically singular equation. However, the corresponding
estimates deteriorate as $m\to0$. It is shown that these estimates
become stable and carry to the limit as $m\to0$, provided the
indicated sufficiently high order of integrability is in force. The
latter then appears as the discriminating assumption between
solutions of parabolic equations with power-like singularities and
logarithmic singularities to insure such solutions to be regular.
[50] A. Björn, J. Björn, U. Gianazza and M. Parviainen -
Boundary regularity for degenerate and singular parabolic
equations - Calc.
Var., 52(3) (2015), 797-827.
Abstract: We
characterise regular boundary points of the parabolic $p$-Laplacian
in terms of a family of barriers, both when $p>2$ and $p\in(1,2)$.
Due to the fact that $p\not=2$, it turns out that one can multiply
the $p$-Laplace operator by a positive constant, without affecting
the regularity of a boundary point. By constructing suitable families
of barriers, we give some simple geometric conditions that ensure the
regularity of boundary points.
[49] V. Bögelein, F. Duzaar and U. Gianazza - Porous
medium type equations with measure data and potential estimates -
SIAM J. Math. Anal.,
45(6), (2013), 3283-3330.
Abstract: We consider
non-homogeneous, degenerate ($m>1$) porous medium type equations
with a non-negative Radon measure $\mu$ having finite total mass
$\mu(E_T)$ on the right-hand side, and we derive linear pointwise
estimates for solutions via Riesz potentials. Then, we deal with a
Cauchy-Dirichlet problem for the same equation, with homogeneous
boundary conditions on the parabolic boundary of the domain $E_T$,
and we establish the existence of a solution in the sense of
distributions.
[48] U. Gianazza - List of Mathematical Works Authored or Edited
by Enrico Magenes - in F. Brezzi et al., (eds), Analysis and Numerics of Partial Differential Equations. Springer INdAM Series, vol 4. Springer, Milano, 2013.
Abstract:The following list of mathematical works authored or edited by Enrico Magenes in his long career has been compiled relying on a number of different sources, and it is probably the first one ever prepared.
[47] E. Dallago, D.G. Finarelli, U. Gianazza, A. Lazzarini
Barnabei and A. Liberale - Theoretical and experimental analysis
of an MPP detection algorithm employing a single voltage sensor only
and a noisy signal - IEEE
Transactions on Power Electronics, vol.28(11), (2013), 5088-5097.
Abstract: In this paper, a maximum power point (MPP)
detection algorithm for photovoltaic (PV) systems is introduced,
which uses the experimental information obtained from a
single-voltage sensor, measured on a capacitor load, either linked at
the output of a solar cell (SC), a PV module, or a PV string. The
voltage signal is naturally affected by the noise which has a
relevant effect on the process necessary for MPP determination, such
as voltage first- and second-order derivatives. The aim of this study
is to demonstrate the technical feasibility of a maximum power point
tracker (MPPT) based on the present MPP detection algorithm employing
a single-voltage sensor acquiring a signal affected by the
significant noise. Theoretical evaluation, numerical simulations, and
experimental measurements are carried out. Excellent agreement
between the theoretical and experimental behavior is observed.
Conditions for correct MPP detection are shown and good performances
are obtained.
[46] E. DiBenedetto, U. Gianazza and V. Vespri - Continuity of
the Saturation in the Flow of Two Immiscible Fluids in a Porous
Medium - Indiana
Univ. Math. J. 59 No. 6 (2010), 2041-2076.
Abstract:
The weakly coupled system \begin{equation*} \left\{ \begin{array}{l}
{\displaystyle v_t-{\operatorname{div}}[A(v)\nabla v+{\bf B}(v)]={\bf
V}\cdot\nabla C(v)}\\ {\displaystyle {\operatorname{div}}{\bf V}=0}
\end{array}\right. \qquad\text{ in }\>E_T. \end{equation*}
consists of an elliptic equation and a degenerate parabolic equation,
and it arises in the theory of flow of immiscible fluids in a porous
medium. The unknown functions $u$ and $v$ and the equations they
satisfy, represent the pressure and the saturation respectively,
subject to Darcy's law and the Buckley--Leverett coupling. Due to the
empirical nature of these laws no determination is possible on the
structure of the degeneracy exhibited by the system. It is
established that the saturation is a locally continuous function in
its space--time domain of definition, irrespective of the nature of
the degeneracy of the principal part of the system.
[45] E. DiBenedetto, U. Gianazza and N. Liao - Logarithmically
Singular Parabolic Equations as Limits of the Porous Medium Equation
- Nonlinear
Analysis Series A: Theory, Methods & Applications, 75(12),
(2012), 4513-4533.
Abstract: Let $\{u_m\}$ be a
local, weak solution to the porous medium equation \begin{equation*}
u_{m,t}-\Delta w_m=0 \end{equation*} where $w_m=\frac{u_m^m-1}{m}$.
It is shown that if $\{u_m\}$ is locally in $L^r_{loc}$ for
$r>\frac12N$ uniformly in $m$ and if $w_m$ is in $L^p_{loc}$ for
$p>N+2$ in the space variables, uniformly in time, then $\{u_m\}$
contains a subsequence converging in $C^{\alpha,\frac12\alpha}_{loc}$
to a local, weak solution to the logarithmically singular equation
$u_t=\Delta\ln u$. The result is based on local upper and lower
bounds on $\{u_m\}$, uniform in $m$. The uniform, local lower bounds
are realized by a Harnack type inequality.
[44] E. DiBenedetto, U. Gianazza and N. Liao - On the Local
Behavior of Non-Negative Solutions to a Logarithmically Singular
Equation - Discrete
Continuous Dynamical Systems Ser. B, 17(6), (2012), 1841-1858.
Abstract: The local positivity of solutions to
logarithmically singular diffusion equations is investigated in some
open space-time domain $E\times(0,T]$. It is shown that if at some
time level $t_o\in(0,T]$ and some point $x_o\in E\,$ the solution
$u(\cdot,t_o)$ is not identically zero in a neighborhood of $x_o$, in
a measure-theoretical sense, then it is strictly positive in a
neighborhood of $(x_o,t_o)$. The precise form of this statement is by
an intrinsic Harnack-type inequality, which also determines the size
of such a neighborhood.
[43] E. DiBenedetto, U. Gianazza and V. Vespri - Liouville-Type
Theorems for Certain Degenerate and Singular Parabolic Equations
- C. R. Acad.
Sci. Paris, Ser. I 348 (2010) 873-877.
[42] E. DiBenedetto, U. Gianazza and V. Vespri - Forward,
Backward and Elliptic Harnack Inequalities for Non-Negative Solutions
to Certain Singular Parabolic Partial Differential Equations -
Ann. Scuola
Norm. Sup. Pisa Cl. Sci. (5), Vol. IX (2010), 385-422.
[41] E. DiBenedetto, U. Gianazza and V. Vespri - A New Approach
to the Expansion of Positivity Set of Non-negative Solutions to
Certain Singular Parabolic Partial Differential Equations - Proc.
Amer. Math. Soc. 138 (2010), 3521-3529.
[40] U. Gianazza, M. Surnachev and V. Vespri - On a new proof
of Hölder continuity of solutions of p-Laplace type parabolic
equations - Adv.
Calc. Var. 3 (2010), 263-278.
[39] E. DiBenedetto, U. Gianazza and V. Vespri - Harnack Type
Estimates and Hölder Continuity for Non-Negative Solutions to
Certain Sub-Critically Singular Parabolic Partial Differential
Equations - manuscripta
mathematica, 131, (1-2), (2010), 231-245.
[38] S. Fornaro, U. Gianazza - Local properties of non-negative
solutions to some doubly non-linear degenerate parabolic equations
- Discrete and
Continuous Dynamical Systems A, 26, (2), (2010), 481-492.
[37] E. DiBenedetto, U. Gianazza and V. Vespri - Alternative
Forms of the Harnack Inequality for Non-Negative Solutions to Certain
Degenerate and Singular Parabolic Equations - Rendiconti
Lincei Matematica ed Applicazioni, 20(4), (2009), 369-377.
[36] U. Gianazza, G. Savaré, G. Toscani - The
Wasserstein gradient flow of the Fisher information and the Quantum
Drift-Diffusion equation - Arch.
Rational Mech. Analysis, 194, (1), (2009) 133-220.
[35] E. DiBenedetto, U. Gianazza, V. Vespri - Harnack Estimates
for Quasi-Linear Degenerate Parabolic Differential Equation -
Acta
Mathematica, 200 (2008), 181-209.
[34] L. Corazzini, U. Gianazza - Unequal contributions from
identical agents in a local interaction model - Journal
of Public Economic Theory, 10 (3), 2008, 351-370.
[33] E. DiBenedetto, U. Gianazza, V. Vespri - Sub-Potential
Lower Bounds for Non-Negative Solutions to Certain Quasi-Linear
Degenerate Parabolic Differential Equations - Duke
Mathematical Journal, Vol. 143, 1, (2008), 1-15.
[32] U. Gianazza, S. Polidoro - Lower Bounds for Solutions of
Degenerate Parabolic Equations - Lecture Notes of Seminario
Interdisciplinare di Matematica, Vol. 6(2007), 157-162.
[31] F. Dinuzzo, M. Neve, U. Gianazza, G. De Nicolao - On the
representer theorem and equivalent degrees of freedom of SVR -
Journal
of Machine Learning Research 8 (2007), 2467-2495.
[30] E. DiBenedetto, U. Gianazza and V. Vespri - Intrinsic
Harnack Inequalities for Quasi-linear Singular Parabolic Partial
Differential Equations - Rend.
Lincei Mat. Appl. 18 (2007), 359-364.
[29] E. DiBenedetto, U. Gianazza, V. Vespri - Intrinsic Harnack
estimates for non-negative local solutions of degenerate parabolic
equations - Electron.
Res. Announc. Amer. Math. Soc. 12 (2006), 95-99.
[28] E. DiBenedetto, U. Gianazza, V. Vespri - Local Clustering
of the Non-Zero Set of Functions in W1,1(E)
- Rend.
Lincei Mat. Appl. 17, (2006), 223-225.
[27] U. Gianazza, V. Vespri - A Harnack Inequality for a
Degenerate Parabolic Equation - Journal
of Evolution Equations, 6, 2, (2006), 247-267.
[26] U. Gianazza, V. Vespri - Parabolic De Giorgi classes of order p and the Harnack inequality- Calculus
of Variations and Partial Differential Equations, 26, 3, (2006),
379-399.
[25] U. Gianazza, V. Vespri - A Harnack Inequality for
Solutions of Doubly Nonlinear Parabolic Equations - Journal
Applied Functional Analysis, 1, 3, (2006), 271-284.
[24] U. Gianazza, B. Stroffolini, V. Vespri - Interior and
boundary continuity of the solution of the singular equation
(β(u))t=Lu - Nonlinear
Anal. 56, 2, (2004) 157-183.
[23] U. Gianazza, V. Vespri - Continuity of weak solutions of a
singular parabolic equation - Advances
in Differential Equations, 8, 11, (2003), 1341-1376.
[22] U. Gianazza, V. Vespri - The Heisenberg Laplacian: a
survey - Rend. Circolo Matem. Palermo Serie II, Suppl. 52 (1998).
pp. 491-512.
[21] U. Gianazza, V. Vespri - Hölder Classes relative to
degenerate Elliptic Operators as Interpolation Spaces - Ulmer
Seminare 1997, Funktionalanalysis und Differentialgleichungen, Heft2,
367-376, Le Matematiche, Vol LIII, (1998) - Fasc. I, 107 - 121.
[20] U. Gianazza - Existence for a nonlinear problem relative
to Dirichlet forms - Rend. Acc. Naz. XL, 115 (1997), Vol. XXI,
fasc. 1, 209-234.
[19] U. Gianazza, V. Vespri - Analytic Semigroups generated by
Square Hörmander Operators - Rend. Istit. Mat. Univ.
Trieste, Suppl. Vol. XXVIII, 199-218 (1997).
[18] U. Gianazza - Regularity for a degenerate obstacle problem
- IAN preprint # 997.
[17] U. Gianazza, V. Vespri - Generation of Analytic semigroups
by Degenerate Elliptic Operators - NoDEA,
4 (1997) 305-324.
[16] U. Gianazza, S. Marchi - Interior regularity for solutions
to some degenerate quasilinear obstacle problems - Nonlinear
Anal. 36 (1999), no. 7, Ser. A: Theory Methods, 923-942.
[15] U. Gianazza, G. Savaré - Abstract Evolution
Equations on Variable Domains: An Approach by Minimizing Movements
- Ann.
Scuola Norm. Sup. Pisa, IV, XXIII, 1, (1996), 149-178.
[14] U. Gianazza - Meyer's estimate for Dirichlet forms -
Rend. Ist. Lomb. A, 128, (1994) 147-151.
[13] U. Gianazza, G. Savaré - Some results on Minimizing
Movements - Rend. Acc. Naz. XL, 112, (1994), XVIII, fasc. 1,
57-80.
[12] U. Gianazza, M. Gobbino, G. Savaré - Evolution
Problems and Minimizing Movements - Rend. Mat. Acc. Lincei, s. 9,
v. 5:289-296 (1994).
Abstract: We recall the definition of Minimizing Movements,
suggested by E. De Giorgi, and we
consider some applications to evolution problems. With regards to ordinary differential equations, we
prove in particular a generalization of maximal slope curves theory to arbitrary metric spaces. On the other
hand we present a unifying framework in which some recent conjectures about partial differential equations
can be treated and solved. At the end we consider some open problems.
[11] M. P. Bernardi, E. Gagliardo, U. Gianazza - Proprietà
di combinazioni lineari intere. Applicazioni - Rend. Ist. Lomb.
A, 127, (1993) 33-39.
[10] U. Gianazza - Limit of obstacles for square Hörmander
operators - Atti Sem. Mat. Fis. Univ. Modena, XLIII, 467-471
(1995).
[9] U. Gianazza - Sequences of obstacles problems for Dirichlet
forms - Diff.
Int. Eq., 9, (1996), 89-118.
[8] U. Gianazza - Higher integrability for Quasi-minima of
functionals depending on vector fields - Rend. Acc. Naz. XL, 111
(1993), Vol. XVII, fasc. 1, 209-227.
[7] U. Gianazza - Regularity for non linear equations involving
square Hörmander operators - Nonlinear
Analysis: Theory, Methods & Applications, 23(1), (1994), 49-73.
[6] U. Gianazza - The Lp integrability
on homogeneous spaces - Rend. Ist. Lomb. A, 126, (1992) 83-92.
[5] U. Gianazza - Local properties of variational solutions for
the two obstacle problem involving square Hörmander operators
- Ann. Mat. Pura
Appl., (IV), 164, (1994), 301-333.
Abstract: We consider the double obstacle problem involving square Hörmander operators. We prove a Wiener estimate giving a generalization of results obtained both for degenerate elliptic operators and for uniformly elliptic operators with bounded and measurable coefficients.
[4] M. Biroli, U. Gianazza - Wiener criterion for the obstacle
problem relative to square Hörmander's operators -
Variational and Free Boundary Problems. IMA Volumes in Mathematics
and its Applications 53.
[3] U. Gianazza - Potential estimate for the obstacle problem
relative to the sum of squares of vector fields - Riv. Mat. Univ.
Parma, (4) 17 (1991) 221 - 239.
[2] U. Gianazza - Wiener points and energy decay for a relaxed
Dirichlet problem relative to a degenerate elliptic operator -
Riv. Mat. Univ. Parma (4) 16 (1990) 297 - 309.
[1] U. Gianazza - Soluzioni forti per un problema ellittico
degenere - Rend. Ist. Lomb. A, 124, (1990) 189 - 206.
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