Copyright © 2009 Patrick J. Rabier. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
We fill a gap in the theory of elliptic systems on bounded domains, by proving the -independence of the index and null-space under “minimal” smoothness assumptions. This result has been known for long if additional regularity is assumed and in various other special cases, possibly for a limited range of values of . Here, -independence is proved in full generality.