Roger Hui wrote: > I put into the Errata only things that I know > for certain are incorrect. It is debateable whether > DeMorgan is incorrect (esp. when used twice).
I think DeMorgan was meant, even though it is not correct. See for example http://books.google.com/books?id=GzMAAAAAQAAJ&printsec=titlepage&source=gbs_summary_r&cad=0 Best wishes, John ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
