Article
Keywords:
semiconcave functions; singularities
Summary:
P. Albano and P. Cannarsa proved in 1999 that, under some applicable conditions, singularities of semiconcave functions in $\mathbb R^n$ propagate along Lipschitz arcs. Further regularity properties of these arcs were proved by P. Cannarsa and Y. Yu in 2009. We prove that, for $n=2$, these arcs are very regular: they can be found in the form (in a suitable Cartesian coordinate system) $\psi(x) = (x, y_1(x)-y_2(x))$, $x\in [0,\alpha]$, where $y_1$, $y_2$ are convex and Lipschitz on $[0,\alpha]$. In other words: singularities propagate along arcs with finite turn.
References:
[1] Albano P., Cannarsa P.:
Structural properties of singularities of semiconcave functions. Ann. Scuola Norm. Sup. Pisa Cl. Sci. (4) 28 (1999), 719–740.
MR 1760538 |
Zbl 0957.26002
[3] Cannarsa P., Sinestrari C.:
Semiconcave Functions, Hamilton-Jacobi Equations, and Optimal Control. Progress in Nonlinear Differential Equations and their Applications, 58, Birkhäuser, Boston, 2004.
MR 2041617 |
Zbl 1095.49003
[4] Clarke F.H.:
Optimization and nonsmooth analysis. 2nd edition, Classics in Applied Mathematics, 5, SIAM, Philadelphia, 1990.
MR 1058436 |
Zbl 0696.49002
[8] Pavlica D.:
On the points of non-differentiability of convex functions. Comment. Math. Univ. Carolin. 45 (2004), 727–734.
MR 2103086 |
Zbl 1100.26006
[10] Veselý L., Zajíček L.:
Delta-convex mappings between Banach spaces and applications. Dissertationes Math. (Rozprawy Mat.) 289 (1989).
MR 1016045
[11] Veselý L., Zajíček L.:
On vector functions of bounded convexity. Math. Bohemica 133 (2008), 321–335.
MR 2494785
[12] Zajíček L.:
On the differentiation of convex functions in finite and infinite dimensional spaces. Czechoslovak Math. J. 29 (1979) 340–348.
MR 0536060