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In this paper we give a complete answer to the famous gradient problem of C. E. Weil. On an open set G ⊂ R2 we construct a differentiable function f: G → R for which there exists an open set Ω1 ⊂ R2 such that ∇f(p) ∈ Ω1 for a p ∈ G but ∇f(q) ∉ Ω1 for almost every q ∈ G. This shows that the Denjoy-Clarkson property does not hold in higher dimensions.
Buczolich, Zoltán. "Solution to the gradient problem of C.E. Weil.." Revista Matemática Iberoamericana 21.3 (2005): 889-910. <http://eudml.org/doc/41954>.
@article{Buczolich2005, abstract = {In this paper we give a complete answer to the famous gradient problem of C. E. Weil. On an open set G ⊂ R2 we construct a differentiable function f: G → R for which there exists an open set Ω1 ⊂ R2 such that ∇f(p) ∈ Ω1 for a p ∈ G but ∇f(q) ∉ Ω1 for almost every q ∈ G. This shows that the Denjoy-Clarkson property does not hold in higher dimensions.}, author = {Buczolich, Zoltán}, journal = {Revista Matemática Iberoamericana}, keywords = {Funciones diferenciables; Gradientes; Teoría de la medida; Denjoy-Clarkson property; Lebesgue measure}, language = {eng}, number = {3}, pages = {889-910}, title = {Solution to the gradient problem of C.E. Weil.}, url = {http://eudml.org/doc/41954}, volume = {21}, year = {2005}, }
TY - JOUR AU - Buczolich, Zoltán TI - Solution to the gradient problem of C.E. Weil. JO - Revista Matemática Iberoamericana PY - 2005 VL - 21 IS - 3 SP - 889 EP - 910 AB - In this paper we give a complete answer to the famous gradient problem of C. E. Weil. On an open set G ⊂ R2 we construct a differentiable function f: G → R for which there exists an open set Ω1 ⊂ R2 such that ∇f(p) ∈ Ω1 for a p ∈ G but ∇f(q) ∉ Ω1 for almost every q ∈ G. This shows that the Denjoy-Clarkson property does not hold in higher dimensions. LA - eng KW - Funciones diferenciables; Gradientes; Teoría de la medida; Denjoy-Clarkson property; Lebesgue measure UR - http://eudml.org/doc/41954 ER -