文摘
The author establishes some geometric criteria for a Hajx142;asz–Sobolev -extension (resp. -imbedding) domain of with n2, s(0,1] and p[n/s,∞] (resp. p(n/s,∞]). In particular, the author proves that a bounded finitely connected planar domain Ω is a weak α-cigar domain with α(0,1) if and only if for some/all s[α,1) and p=(2−α)/(s−α), where denotes the restriction of the Triebel–Lizorkin space on Ω.