Onn-widths of bounded periodic holomorphic functions

The even-dimensional Kolmogorov widthsd _2n , Gel'fand widthsd ²ⁿ , and linear widths _2n ofà inL _q andC are determined exactly. We show that all threen-widths are equal and give a characterization of the widths in terms of Blaschke products.Published in Ukrainskii Matematicheskii Zhurnal, Vol. 47, No. 9, pp. 1170–1175, September, 1995.