© 2004 by London Mathematical Society
© The London Mathematical Society
Approximation Numbers of Sobolev Embedding Operators on an Interval

Department of Mathematics, Lund University Box 118, 221 00, Sweden christer.bennewitz{at}math.lu.se
Department of Mathematics, University of Alabama Birmingham, AL 35 294, USA, saito{at}math.uab.edu
Received 9 July 2003.
Consider the Sobolev embedding operator from the space of functions in W1,p(I) with average zero into Lp, where I is a finite interval and p>1. This operator plays an important role in recent work. The operator norm and its approximation numbers in closed form are calculated. The closed form of the norm and approximation numbers of several similar Sobolev embedding operators on a finite interval have recently been found. It is proved in the paper that most of these operator norms and approximation numbers on a finite interval are the same.