# A Reward Check From Donald Knuth

The other day I went to my pigeon-hole to collect my snail mail, and I had a letter from Donald E. Knuth, Professor Emeritus of the Art of Computer Programming!

Inside, there was a check for a correction I sent him some months ago. In fact, it was not really a correction; it was more like a comment. And it was so obvious (he even said that) that he just sent $0.32, instead of the usual$2.56. But hey, who cares? I’ve got Knuth’s autograph now! :-)

Perhaps I should set as one of my goals to find a proper error, so that I can receive a $2.56 check :-) By the way, the errata of the Concrete Mathematics is available online and this particular omission is documented as follows: page 338, line 2 from the bottom change “for$z$” to “for$z$and multiplying by$a\$”

##### João F. Ferreira
###### Computer Scientist

My research interests include software reliability, software verification, and formal methods applied to software engineering. I am also interested in interactive storytelling. For more details, see some of my projects or my selected (or recent) publications. More posts are available in my blog. Follow me on Twitter or add me on LinkedIn.