[HN Gopher] Discovering errors in Donald Knuth's TAOCP
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Discovering errors in Donald Knuth's TAOCP
Author : glth
Score : 98 points
Date : 2025-03-08 16:27 UTC (6 hours ago)
(HTM) web link (glthr.com)
(TXT) w3m dump (glthr.com)
| WillAdams wrote:
| Nice! When I reported an error and a point of improvement in
| _Digital Typography_ the address was printed and glued on, not
| hand-written, which somewhat detracts from the display of the
| check/envelope.
|
| Need to find another error so I can get an account....
| dmoy wrote:
| This makes me feel less bad about also not being able to figure
| out my printer's address printing function.
|
| Like I know it is capable. I know how to set up the hand feed
| for it (and I successfully do that for thicker paper). And
| ostensibly I know the right dimensions and how to line it up in
| a PDF. But then it's just failure after failure, and I go back
| to cut and paste or handwrite.
| WillAdams wrote:
| Really miss poste.app on my NeXT Cube, which was a small
| app/service which did nothing but print a selected address
| onto a hand-fed envelope.
| nwellnhof wrote:
| The inventor of the bug bounty.
| jgrahamc wrote:
| I have a Knuth cheque from back when he sent out real cheques. Or
| at least I did; for some reason I decided that cashing it was a
| good idea and so I have his note back to me and a photocopy of
| the actual cheque.
| belter wrote:
| What error did you find?
| secondcoming wrote:
| Aren't the cheques for $2.56?
| hinkley wrote:
| Why am I just now having this thought?
|
| He should make them $5.12 so it's a check for 1,000,000,000
| cents, instead of 100,000,000.
| cinntaile wrote:
| lol I'm a bit curious about the thought process that led you to
| decide you wanted to cash it.
| zabzonk wrote:
| A long while back I wrote an answer on Stack Overflow to a
| question that asked "How to read TAOCP?" my answer looked
| something like this:
|
| - don't read them
|
| - get all the books, put them in a bin bag and shake vigorously
| with some lumps of coal, to give them that "used" look
|
| - go through the books, underline things at random and make notes
| (also at random) in the margin such as "how true", or even better
| "wrong!"
|
| - put books on shelf in office - never look at them again
|
| This has worked for me, though I must admit that Searching &
| Sorting and stuff about random numbers are pretty good.
|
| I got my copies free from Addison Wesley for doing some book
| reviews for them - not reviewing Knuth, needless to say!
| WillAdams wrote:
| I have worked with two programmers who had well-thumbed copies
| of TAoCP on their shelves which each had actually read (one was
| the only other person I've met outside of a TeX conference who
| had a reward check) --- to this day, I've not worked with
| better devs.
| nickdrozd wrote:
| Great post. Some general takeaways for people who want Knuth
| checks:
|
| 1. You are unlikely to find errors in the algorithms themselves,
| especially if they've been officially published. You might find
| some infelicities, but these are not counted as full errors. For
| example, the author here found some confusing-but-not-wrong
| comments about local variables and unused registers. These are
| counted as "suggestions" (worth 0x20C/) rather than "errors"
| (worth 0x$1.00).
|
| 2. Knuth is pretty generous with credit -- if your suggestion
| leads him to find an error, you get credit for the error. The
| author here said that some defined variables went unused. Knuth
| pointed out that those variables were in fact used in an
| exercise. However, in looking this up he noticed a variable-
| related error in that exercise. Author is credited with 0x$1.00!
|
| 3. Exercises are more likely to contain errors and infelicities
| than the main text. And there are an awful lot of exercises.
|
| 4. Knuth includes a whole bunch of stuff in his books that is not
| related to CS. Lots of weird trivia and references. This stuff is
| more likely to be wrong than the main text. For example, Knuth
| mentions "icosahedral objects inscribed with Greek letters" and
| includes a reference to an article in the _Bulletin de l'Institut
| francais du Caire_. But the author points out that the article is
| actually in the _Bulletin de l'Institut francais d'archeologie
| orientale_. Whoops! 0x$1.00 for you!
| Tomte wrote:
| Don't make assumptions about what parts must have been combed
| through so much that there is no chance of finding annerror.
|
| I found one and got my cheque on page Arabic one in one of his
| books. Paragraph one. First sentence. The very first word.
| eigenvalue wrote:
| Was it the word "the" instead of "a"? Trying to think what
| else it could even be.
| dalke wrote:
| I found an error in a published version of TAOCP, 2nd edition I
| think, with improvements on Sieve of Eratosthenes. I was so
| excited, then found it was already listed in the errata.
|
| I later got a check for identifying a minor issue with the
| early history of superimposed coding. I happen to have copies
| of the relevant patent case containing examples predating
| Mooers' _randomized_ superimposed coding.
|
| ("Happened to" because I had visited the Mooers archive at the
| Charles Babbage Institute in Minnesota to research some of the
| early history of chemical information management. Mooers is one
| of the "fathers" of information retrieval, and in fact coined
| the term "information retrieval" at a chemistry conference.)
| hinkley wrote:
| Knuth has the Pablo Picasso's Dinner Bill "Problem" and so can
| afford to be generous.
|
| Picasso used to dine and dash as it were by drawing a doodle on
| the back of his check when the bill came due, and often enough
| the owner would choose to frame the check instead of cash it.
|
| For a long time most of the cost of writing checks to Knuth is
| the writing of the checks, not the cashing of them. He's paying
| for X00 checks at a time and the energy to fill them out. And
| anyone who had gotten their first check from him would not cash
| it.
|
| Though these days I can cash a check via a phone app and so I
| don't need to forfeit the check to get the money.
| fastasucan wrote:
| >Though these days I can cash a check via a phone app and so
| I don't need to forfeit the check to get the money.
|
| Its incredible that both of these technologies is in active
| use at the same time.
| zozbot234 wrote:
| > ... includes a reference to an article in the _Bulletin de
| l'Institut francais du Caire_. But the author points out that
| the article is actually in the _Bulletin de l'Institut francais
| d'archeologie orientale_. Whoops! 0x$1.00 for you!
|
| I do wonder whether this is more likely to be a case where the
| journal actually changed its name over time (perhaps because
| the _Institut_ itself did) and then made the older papers
| available under the new name - which would mean both references
| are ultimately correct.
| gblargg wrote:
| Does the bank really read the amounts as hexadecimal?
| jks wrote:
| He used to send out real cheques for $2.56 but apparently they
| contained codes that could be used to transfer money out of his
| account in excess of the sum of the cheque. Now he uses the
| made-up Bank of San Serriffe, which naturally understands
| hexadecimal.
|
| https://www-cs-faculty.stanford.edu/~knuth/news08.html
| jll29 wrote:
| I've emailed DEK to point out that the first person to break
| Enigma was not actually Alan M. Turing (as stated in one of the
| recent pre-fascicles) but the Polish mathematician Marian
| Rejewski (Turing's contribution was to automate the task, which
| was important because the rotors/settings were reconfigured by
| the German Wehrmacht every morning).
|
| Bletchley Park now has a prominent bust of Rejewski that credits
| his accomplishment. The Polish wisely passed on their knowledge
| to the British to keep the intel safe, because they expected a
| German invasion.
|
| On another note, I hope Professor Knuth has a continuity plan in
| place that ensures that his book series gets completed despite
| his advanced age (I'm worried about that, but tact prohibited me
| from asking, of course).
| WillAdams wrote:
| Given his quite healthy lifestyle, I believe that we should be
| okay on that latter front --- I certainly hope so.
| irrational wrote:
| It's not his lifestyle I'm worried about. There was a healthy
| youtuber who made videos about wilderness survival who was
| killed when he was rear ended by a drunk driver while stopped
| at a red light (the drunk driver, of course, survived). It's
| all the morons around Knuth I'm worried about.
| mmooss wrote:
| OT: Will Knuth's lifetime of work be used for learning input in
| AI systems, and does he control that?
|
| An AI application might make a good search interface for Knuth's
| opus.
| lysace wrote:
| The key players have likely all ingested Anna's Archive.
| mmooss wrote:
| Based on what you say, I presume that Anna's Archive includes
| Knuth. For certain purposes, would you want AI software
| trained only on Knuth or have it 'diluted' with everything
| else?
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(page generated 2025-03-08 23:00 UTC)