The papers here appear in several formats. They were originally written in successive versions of EXP, and these files, with an extension .wxp, may be read and printed (on a 32-bit PC under Windows 95 or later) with the program Viewer.exe, which is downloadable from www.expswp.com. The files with extension .pdf and .ps, where provided, are readable with Acrobat Reader 4 or later or with GhostView (etc.) The files with extension .tex are translations to LaTeX2e, with the additions provided by AMS-LaTeX v1.2 or later. They invoke also two of the three EXP style files exptex.sty, expthmi.sty, expthmic.sty, included on this directory. The various versions are NOT absolutely equivalent, for various reasons; LaTeX conventions have changed the appearance of those versions quite substantially, and the papers that have since been published have also undergone slight changes to improve their final appearance. In short, the versions here are not the final ones and may contain numerous infelicities and minor errors, but I hope they are accurate enough from the mathematical point of view.