Abstract
Let R(D) be the algebra generated in Sobolev space W 22(D) by the rational functions with poles outside the unit disk \( \overline D \). In this paper the multiplication operators M g on R(D) is studied and it is proved that M g ∼ \( M_{z^n } \) if and only if g is an n-Blaschke product. Furthermore, if g is an n-Blaschke product, then M g has uncountably many Banach reducing subspaces if and only if n > 1.
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This work was supported by the National Natural Science Foundation of China (Grant No. 10471041)
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Wang, Z., Zhao, R. & Jin, Y. Finite Blaschke product and the multiplication operators on Sobolev disk algebra. Sci. China Ser. A-Math. 52, 142–146 (2009). https://doi.org/10.1007/s11425-008-0051-x
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DOI: https://doi.org/10.1007/s11425-008-0051-x