A brief correction to a problem that may have already been noticed and rectified: on page 84 (being page 104 of the PDF), in the last sentence of section 6.4.3, it reads: "0**y is 1 if y is 1, and 0 otherwise." Surely this should read "0**y is 1 if y is 0, and 0 otherwise", yes? Best regards, Peter Klausler at Google in Madison