“…Note also that, if 1 ≤ p < n, then there are very pathological examples of Sobolev homeomorphisms with the Jacobian equal zero a.e. The first such example was constructed by Hencl [20], see also [5,8].…”
Section: Introduction and Resultsmentioning
confidence: 99%
“…Chain rule. The main result of [8] (see also [33]) provides an example of a surjective homeomorphism f : (0, 1) n → (0, 1) n , n ≥ 3, such that f ∈ W 1,1 , f −1 ∈ W 1,1 and J f = 0 a.e., J f −1 = 0 a.e. Note that f −1 • f = Id, but the chain rule…”
Section: Preliminariesmentioning
confidence: 99%
“…Denote the points of the cube (0, 1) n by (x, y) ∈ (0, 1) n−ℓ × (0, 1) ℓ = (0, 1) n and define f x (y) = f (x, y), f i,x (y) = f i (x, y). Then for almost all x ∈ (0, 1) n−ℓ we have f x , f i,x ∈ W 1,p (0, 1) ℓ and there is a subsequence f i j such that for almost all x ∈ (0, 1) n−ℓ (8) lim…”
Section: Lemma 18 (The Lebesgue Differentiation Theoremmentioning
We investigate a known problem whether a Sobolev homeomorphism between domains in R n can change sign of the Jacobian. The only case that remains open is whenand either f is Hölder continuous on almost all spheres of dimension [n/2], or f −1 is Hölder continuous on almost all spheres of dimensions n − [n/2] − 1, then the Jacobian of f is non-negative, J f ≥ 0, almost everywhere. This result is a consequence of a more general result proved in the paper. Here [x] stands for the greatest integer less than or equal to x.
“…Note also that, if 1 ≤ p < n, then there are very pathological examples of Sobolev homeomorphisms with the Jacobian equal zero a.e. The first such example was constructed by Hencl [20], see also [5,8].…”
Section: Introduction and Resultsmentioning
confidence: 99%
“…Chain rule. The main result of [8] (see also [33]) provides an example of a surjective homeomorphism f : (0, 1) n → (0, 1) n , n ≥ 3, such that f ∈ W 1,1 , f −1 ∈ W 1,1 and J f = 0 a.e., J f −1 = 0 a.e. Note that f −1 • f = Id, but the chain rule…”
Section: Preliminariesmentioning
confidence: 99%
“…Denote the points of the cube (0, 1) n by (x, y) ∈ (0, 1) n−ℓ × (0, 1) ℓ = (0, 1) n and define f x (y) = f (x, y), f i,x (y) = f i (x, y). Then for almost all x ∈ (0, 1) n−ℓ we have f x , f i,x ∈ W 1,p (0, 1) ℓ and there is a subsequence f i j such that for almost all x ∈ (0, 1) n−ℓ (8) lim…”
Section: Lemma 18 (The Lebesgue Differentiation Theoremmentioning
We investigate a known problem whether a Sobolev homeomorphism between domains in R n can change sign of the Jacobian. The only case that remains open is whenand either f is Hölder continuous on almost all spheres of dimension [n/2], or f −1 is Hölder continuous on almost all spheres of dimensions n − [n/2] − 1, then the Jacobian of f is non-negative, J f ≥ 0, almost everywhere. This result is a consequence of a more general result proved in the paper. Here [x] stands for the greatest integer less than or equal to x.
“…Let us then concentrate ourselves on (4). Assume that x is a Lebesgue point for Du, and that J u (x) = 0; as a consequence, if we call y = u(x) then we have that Du −1 (y) exists and coincides with the inverse of Du(x).…”
The first goal of this paper is to give a short description of the planar bi-Sobolev homeomorphisms, providing simple and self-contained proofs for some already known properties. In particular, for any such homeomorphism u : Ω → ∆, one has Du(x) = 0 for almost every point x for which Ju(x) = 0. As a consequence, one can prove thatNotice that this estimate holds trivially if one is allowed to use the change of variables formula, but this is not always the case for a bi-Sobolev homeomorphism. As a corollary of our construction, we will show that any W 1,1 homeomorphism u with W 1,1 inverse can be approximated with smooth diffeomorphisms (or piecewise affine homeomorphisms) un in such a way that un converges to u in W 1,1 and, at the same time, u −1 n converges to u −1 in W 1,1 . This positively answers an open conjecture (see for instance [11, Question 4]) for the case p = 1.
“…Let us also recall that the Jacobian of a W 1,p , 1 ≤ p < n, Sobolev homeomorphism may behave strangely as it may vanish a.e. (see [22], [11] and [17]). As mentioned before the Jacobian of a homeomorphism cannot change sign if p > [n/2] by [24] and therefore the method of sign-changing Jacobian for providing a counterexample in Theorem 1.1 cannot be improved to p > [n/2].…”
Let Ω ⊂ R n , n ≥ 4, be a domain and 1 ≤ p < [n/2], where [a] stands for the integer part of a. We construct a homeomorphism f ∈ W 1,p ((−1, 1) n , R n ) such that J f = det Df > 0 on a set of positive measure and J f < 0 on a set of positive measure. It follows that there are no diffeomorphisms (or piecewise affine homeomorphisms) f k such that f k → f in W 1,p .
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.