The fascinating homotopy structure of Sobolev spaces (Q2569792)

Summary: We discuss recent developments in the study of the homotopy classes for the Sobolev spaces \(W^{1, p} (M; N)\). In particular, we report on the work of \textit{H. Brezis} and \textit{Y. Li} [J. Funct. Anal. 183, No. 2, 321--369 (2001; Zbl 1001.46019)] and \textit{F. Hang} and \textit{F. Lin} [Acta Math. 191, No. 1, 55--107 (2003; Zbl 1061.46032)].