A nonlinear evolution system with two subdifferentials and monotone differential games

It is shown that the first order multivalued equation for V = V(t, x, y, z) involving the sum of two subdifferentials composed with the partials of V (V_t +f(t, x, y, z) · ▽_xV + β(V_y) + γ(V_z) + h(t, x, y, z) ? 0 a.e.) has a Lipschitz solution. This solution is shown to be the value of a differential game in which the players are restricted to choosing monotone nondecreasing functions of time. Accordingly, the multivalued equation is interpreted as the corresponding Hamilton-Jacobi equation of the game.     

Generalized weak subdifferentials

In this article, generalized weak subgradient (gw-subgradient) and generalized weak subdifferential (gw-subdifferential) are defined for nonconvex functions with values in an ordered vector space. Convexity and closedness of the gw-subdifferential are stated and proved. By using the gw-subdifferential, it is shown that the epigraph of nonconvex functions can be supported by a cone instead of an affine subspace. A generalized lower (locally) Lipschitz function is also defined. By using this definition, some existence conditions of the gw-subdifferentiability of any function are stated and some properties of gw-subdifferentials of any function are examined. Finally, by using gw-subdifferential, a global minimality condition is obtained for nonconvex functions.     

Generalized subdifferentials of the rank function

We give an explicit formula for the generalized subdifferentials; i.e. the proximal subdifferential, the Fréchet subdifferential, the limitting subdifferential and the Clarke subdifferential of the counting function. Then, thanks to theorems of A.S. Lewis and H.S. Sendov, we obtain the corresponding generalized subdifferentials of the rank function.     

Characterization of subdifferentials of a singular convex functional in Sobolev spaces of order minus one

Subdifferentials of a singular convex functional representing the surface free energy of a crystal under the roughening temperature are characterized. The energy functional is defined on Sobolev spaces of order ?1, so the subdifferential mathematically formulates the energy?s gradient which formally involves 4th order spacial derivatives of the surface?s height. The subdifferentials are analyzed in the negative Sobolev spaces of arbitrary spacial dimension on which both a periodic boundary condition and a Dirichlet boundary condition are separately imposed. Based on the characterization theorem of subdifferentials, the smallest element contained in the subdifferential of the energy for a spherically symmetric surface is calculated under the Dirichlet boundary condition.     

Links between subderivatives and subdifferentials

We provide formulas linking the radial subderivative to other subderivatives and subdifferentials for arbitrary extended real-valued lower semicontinuous functions.     

Directional subdifferentials and optimality conditions

This paper is devoted to the introduction and development of new dual-space constructions of generalized differentiation in variational analysis, which combine certain features of subdifferentials for nonsmooth functions (resp. normal cones to sets) and directional derivatives (resp. tangents). We derive some basic properties of these constructions and apply them to optimality conditions in problems of unconstrained and constrained optimization.     

Semi-algebraic functions have small subdifferentials

We prove that the subdifferential of any semi-algebraic extended-real-valued function on $\mathbf{R}^n$ has $n$ -dimensional graph. We discuss consequences for generic semi-algebraic optimization problems.     

Limiting subdifferentials of indefinite integrals

We compute the limiting subdifferential of the indefinite integral of the form where f is an essentially bounded measurable function, or a function continuous on an interval containing (except for, possibly, ), or a step-function which has a countable number of steps around . The related problem of computing the Aumann integral of the limiting subdifferential mapping ∂f(⋅), where f is a Lipschitz real function defined on an open set U⊂Rn, is also investigated.     

ε-Subdifferentials in terms of subdifferentials

In this note, we give a formula which expresses the ε-subdifferential operator of a lower semicontinuous convex proper function on a given Banach space in terms of its subdifferential.     

On the convergence of subdifferentials of convex functions

Research partially supported by NSF grant DMS-9001096. This author would like to thank l'équipe d'analyse convexe of U.S.T.L. Montpellier for its hospitality.     

On the graph convergence of subdifferentials of convex functions

This paper provides another proof of the Attouch Theorem relating the epigraphical limit of sequences of convex functions to the set limit of the graphs of the subdifferentials.

     

Nonsmooth multiobjective optimization using limiting subdifferentials

In this study, using the properties of limiting subdifferentials in nonsmooth analysis and regarding a separation theorem, some weak Pareto-optimality (necessary and sufficient) conditions for nonsmooth multiobjective optimization problems are proved.     

Second-order subdifferentials and convexity of real-valued functions

In this paper we show that the positive semi-definiteness (PSD) of the Fréchet and/or Mordukhovich second-order subdifferentials can recognize the convexity of C¹ functions. However, the PSD is insufficient for ensuring the convexity of a locally Lipschitz function in general. A complete characterization of strong convexity via the second-order subdifferentials is also given.     

Integrability of subdifferentials of directionally Lipschitz functions

Using a quantitative version of the subdifferential characterization of directionally Lipschitz functions, we study the integrability of subdifferentials of such functions over arbitrary Banach space.

     

A note on subdifferentials of pointwise suprema

The paper suggests a new approach to calculation of subdifferentials of suprema of convex functions without any qualification conditions which essentially relies on the Hirriart-Urruty–Phelps formula for subdifferentials of sums of convex l.s.c. functions (also supplied with a simple new proof). The approach in particular provides for a simpler way to (a certain generalization of) the most recent and so far most general formulas of Hantoute–López–Zalinescu and López–Volle.     

Generalized subdifferentials: a Baire categorical approach

We use Baire categorical arguments to construct pathological locally Lipschitz functions. The origins of this approach can be traced back to Banach and Mazurkiewicz (1931) who independently used similar categorical arguments to show that ``almost every continuous real-valued function defined on [0,1] is nowhere differentiable". As with the results of Banach and Mazurkiewicz, it appears that it is easier to show that almost every function possesses a certain property than to construct a single concrete example. Among the most striking results contained in this paper are: Almost every 1-Lipschitz function defined on a Banach space has a Clarke subdifferential mapping that is identically equal to the dual ball; if is a family of maximal cyclically monotone operators defined on a Banach space then there exists a real-valued locally Lipschitz function such that for each ; in a separable Banach space each non-empty weakcompact convex subset in the dual space is identically equal to the approximate subdifferential mapping of some Lipschitz function and for locally Lipschitz functions defined on separable spaces the notions of strong and weak integrability coincide.