I want to thank my colleagues for their comments. I think that some of these appeared to ignore some of my arguments and occasionally indicated a misunderstanding of the points I made. However tempting it is to ‘set the record straight’, I prefer to leave this task to the reader. I wrote my paper aiming at encouraging a discussion of points that, however important, were ignored and simply taken for granted: my colleagues' words demonstrate the importance of such a discussion and I am sure our readers will value our joint text. It will be interesting to learn what comments these readers will make.

Abraham Brafman