Trace spaces at the boundary

Introduce also the spaces iL A(r), A 1, equipped with the norm 

Let n be a unit outer normal to the boundary F. Denote by d /dn the ith order normal derivative at F. We formulate the general trace theorem (Baiocchi, Capelo, 1984). 

Conversely, there exists a linear continuous operator n =o —  

Consider the domain flc with the boundary dflc described in the previous subsection. Let a function u G be given. We assume that dflc 

Lemma 1.12. If the boundary dflc belongs to the class and a function u G iF (f2c) is given, then the normal derivatives at the boundary dflc are uniquely defined. 

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