This article studies the
problem of minimizing
∫ΩF(Du)+G(x,u) over the functions
up://www.sciencedirect.com/scidirimg/entities/2208.gif"" alt=""set membership, variant"" border=0>Wp>1,1p>(Ω) that assume given boundary values
p://www.sciencedirect.com/scidirimg/entities/3d5.gif"" alt=""phi"" border=0> on ∂
Ω. The function
F and the domain
Ω are assumed convex. In considering the same
problem with
e52172df38f4c44e49"" title=""Click to view the MathML source"">G=0, and in the s
pirit of the classical Hilbert–Haar theory,
Clarke has introduced a new ty
pe of hy
pothesis on the boundary function
p://www.sciencedirect.com/scidirimg/entities/3d5.gif"" alt=""phi"" border=0>: the
lower (or u
pper)
bounded slope condition. This condition, which is less restrictive than the classical bounded slo
pe condition of Hartman, Nirenberg and Stam
pacchia, is satisfied if
p://www.sciencedirect.com/scidirimg/entities/3d5.gif"" alt=""phi"" border=0> is the restriction to ∂
Ω of a convex (or concave) function. We show that for a class of
problems in which
G(x,u) is locally Li
pschitz (but not necessarily convex) in
u, the lower bounded slo
pe condition im
plies the local Li
pschitz regularity of solutions.