The AMS is devoted to publishing research mathematics of high quality and significance in all areas of pure and applied mathematics. For journals that appear in dual electronic and print formats, articles are posted individually on the Web soon after proof is returned from authors and before appearing in issues for the print product. The AMS also publishes refereed electronic-only journals that receive the same timely posting that dual-format journals receive. Items in article bibliographies are linked to their reviews on MathSciNet when available.