A Knuth Reward Check

Last week I got a check in the mail from Donald Knuth, for 0x$1.00 ($2.56). Such checks are awarded for being the first to report a particular error in a published work. In this case, it was in a draft for the The Art of Computer Programming. I'm still giddy about it.

The report I sent on April 1st, 2024 in read:

I found two missing names in the index margin notes for Pre-Fascicle 9b (A Potpourri of Puzzles), dated April 22, 2023.

Loyd and Frederickson are both mentioned in the answer to exercise 88 in section 7.2.2.8, but they do not appear in the margin notes for compiling the index.

He replied in pencil:

Frederickson was omitted intentionally, since he is cited in the statement of ex 88. But I should indeed have indexed Loyd.

This is the easiest way to get a reward check, since I didn't have to actually understand the exercise or answer, but Knuth cares about the quality of his index and so it's worth a reward to him.