A locally integrable function has a weak derivative of order α when its derivative of order α in the sense of distributions is represented by a locally integrable function. Sobolev spaces are spaces of differentiable functions with integral norms. In order to define complete spaces, we use weak derivatives. The Sobolev embedding theorem is the most important result of this chapter.
KeywordsWeak derivative Sobolev spaces Sobolev inequality Sobolev embedding theorem.
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