Sobolev approximation by a sum of subalgebras on the circle
Sobolev approximation by a sum of subalgebras on the circle
Let ψ be an orientation-reversing homeomorphism of the unit circle onto itself.We consider approximation in certain Sobolev norms by functions of the form f(z) + g(ψ), where / and g are polynomials.The methods involve conf ormal welding and Hardy space theory.We construct a Jordan arc of positive continuous analytic capacity …