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Donald Knuth's 21st Annual Christmas Lecture: Universal Commafree Codes [video]

97 points by cranium 11y ago

coliveira 11y ago
Usually I don't have any objection against the word Christmas. But in this case I think it is abusive: this talk is not about Christmas and it is not on Christmas day or even close. It seems just a random way of adding the word Christmas to a seminar, maybe only because the speaker happens to be Christian... I would like to believe that Stanford is above this kind of behavior, but sadly it is not.
- spenczar5 11y ago
  As he says in the first 30 seconds of the video, the lecture has been called the "Annual Christmas Tree Lecture" for 20 years, and it was always a lecture about trees in computer science as a bit of a pun. Dr. Knuth said - again, right at the start - that he had trouble finding a good tree-related subject, so he dropped "tree" from the name.
- bdamm 11y ago
  Why should the Christian speaker drop Christmas from the seminar title? It's his seminar, and he gets to decide what to title it. In fact, I think it is offensive to suggest that Christians should sterilize Christian history and iconography from anything they produce. If Donald Knuth decided that his Christian iconography was interfering with the message he wanted to send, then it's his talk and he gets to decide to change the title. If a Jewish/Christian/Muslim professor wants to talk about the 9 Lifos of the Menorah, I don't see a problem with that, either.
- dang 11y ago
  Please let's keep religious flamewars off of HN. Bikeshedding, too, while we're at it.
  - gPphX 11y ago
    The Royal Institution Christmas Lectures are a series of lectures on a single topic, held since 1825, presented scientific subjects to a general audience, in an informative and entertaining manner. Michael Faraday initiated the first Christmas Lecture series in 1825. https://en.wikipedia.org/wiki/Michael_Faraday https://en.wikipedia.org/wiki/Michael_Faraday https://en.wikipedia.org/wiki/Royal_Institution_Christmas_Lectures https://en.wikipedia.org/wiki/Royal_Institution_Christmas_Le...
- copperx 11y ago
  Probably you had a rough Monday and wanted to take it out on HN. If you're being serious, why do you think such trivialities merit discussion? or even a second of your attention? it boggles my mind. We all have intrusive thoughts from time to time, but it is extremely bad form to voice them.
- timthorn 11y ago
  The concept of a Christmas Lecture (or lecture series) as an accessible exposition of a topic is very well established - Faraday kicked them off in 1825 at the Royal Institution.
- udev 11y ago
  Jesus, calm down! (Oops!)
- deleted 11y ago
  [deleted]
- resist_futility 11y ago
  Sorry they forgot that everything has to be secular just for you.
weinzierl 11y ago
If commafree doesn't ring a bell maybe self-synchronizing does. https://en.wikipedia.org/wiki/Prefix_code https://en.wikipedia.org/wiki/Prefix_code
- kazinator 11y ago
  Indeed. This is useful for picking up a transmission in mid-stream at an arbitrary boundary. Or discovering the start of a sector on a disk, as it spins past the read head, spewing whatever bits it finds.
Jabbles 11y ago
Does anyone know why Knuth is writing some form of C? AFAIK none of the other TAOCP contain C, or anything other than (M)MIX and pseudocode. Why change now?
- JonathonW 11y ago
  I haven't watched through the whole thing, but the C code I saw from skipping through looks like it's actually the output from CWEB [1], one of Knuth's literate programming tools. It combines C source code with long-form documentation, and it can either be preprocessed to TeX (to give that nice, pretty printed document that Knuth shows in the video) or to standard C source code to compile and run. CWEB is one of Knuth's languages of choice, and he's got tons of code written in it on his website [2], including versions of some of the stuff he's demoing on-screen. [1] http://www-cs-faculty.stanford.edu/~uno/cweb.html http://www-cs-faculty.stanford.edu/~uno/cweb.html [2] http://www-cs-faculty.stanford.edu/~uno/programs.html http://www-cs-faculty.stanford.edu/~uno/programs.html
- kazinator 11y ago
  Knuth has been using C for quite a long time now (he has not "changed now"), and it's fair to say that he likes it, based on the following: More than 20 years ago, knuth ported his literate programming system to C, resulting in CWEB. Here is a 1993 interview with Knuth about CWEB: http://tex.loria.fr/historique/interviews/knuth-clb1993.html http://tex.loria.fr/historique/interviews/knuth-clb1993.html Key quote (on the subject of C): I think C has a lot of features that are very important. The way C handles pointers, for example, was a brilliant innovation; it solved a lot of problems that we had before in data structuring and made the programs look good afterwards. C isn't the perfect language, no language is, but I think it has a lot of virtues, and you can avoid the parts you don't like. I do like C as a language, especially because it blends in with the operating system (if you're using UNIX, for example). I can only guess that Knuth doesn't use C in TAOCP because C isn't defined in the kind of way that he thinks is suitable for teaching. Every port of C to some given architecture has different parameters which effectively render it a different dialect, and there are undefined behaviors all over the place.
deleted 11y ago
[deleted]
lechevalierd3on 11y ago
For once a news headline with "Donald" not matching Trump.
nikisweeting 11y ago
I was present and unfortunately didn't understand the lecture till I looked up https://en.wikipedia.org/wiki/Huffman_coding https://en.wikipedia.org/wiki/Huffman_coding halfway through. It was very interesting after that point though!
nafizh 11y ago
Saw Donald. Thought, Not again!! Trump at hacker news too!!

97 points by cranium 11y ago

Usually I don't have any objection against the word Christmas. But in this case I think it is abusive: this talk is not about Christmas and it is not on Christmas day or even close. It seems just a random way of adding the word Christmas to a seminar, maybe only because the speaker happens to be Christian... I would like to believe that Stanford is above this kind of behavior, but sadly it is not.

spenczar5 11y ago
As he says in the first 30 seconds of the video, the lecture has been called the "Annual Christmas Tree Lecture" for 20 years, and it was always a lecture about trees in computer science as a bit of a pun. Dr. Knuth said - again, right at the start - that he had trouble finding a good tree-related subject, so he dropped "tree" from the name.
bdamm 11y ago
Why should the Christian speaker drop Christmas from the seminar title? It's his seminar, and he gets to decide what to title it. In fact, I think it is offensive to suggest that Christians should sterilize Christian history and iconography from anything they produce. If Donald Knuth decided that his Christian iconography was interfering with the message he wanted to send, then it's his talk and he gets to decide to change the title. If a Jewish/Christian/Muslim professor wants to talk about the 9 Lifos of the Menorah, I don't see a problem with that, either.
dang 11y ago
Please let's keep religious flamewars off of HN. Bikeshedding, too, while we're at it.
- gPphX 11y ago
  The Royal Institution Christmas Lectures are a series of lectures on a single topic, held since 1825, presented scientific subjects to a general audience, in an informative and entertaining manner. Michael Faraday initiated the first Christmas Lecture series in 1825. https://en.wikipedia.org/wiki/Michael_Faraday https://en.wikipedia.org/wiki/Michael_Faraday https://en.wikipedia.org/wiki/Royal_Institution_Christmas_Lectures https://en.wikipedia.org/wiki/Royal_Institution_Christmas_Le...
copperx 11y ago
Probably you had a rough Monday and wanted to take it out on HN. If you're being serious, why do you think such trivialities merit discussion? or even a second of your attention? it boggles my mind. We all have intrusive thoughts from time to time, but it is extremely bad form to voice them.
timthorn 11y ago
The concept of a Christmas Lecture (or lecture series) as an accessible exposition of a topic is very well established - Faraday kicked them off in 1825 at the Royal Institution.
udev 11y ago
Jesus, calm down! (Oops!)
deleted 11y ago
[deleted]
resist_futility 11y ago
Sorry they forgot that everything has to be secular just for you.

weinzierl 11y ago

If commafree doesn't ring a bell maybe self-synchronizing does. https://en.wikipedia.org/wiki/Prefix_code https://en.wikipedia.org/wiki/Prefix_code

kazinator 11y ago
Indeed. This is useful for picking up a transmission in mid-stream at an arbitrary boundary. Or discovering the start of a sector on a disk, as it spins past the read head, spewing whatever bits it finds.

Jabbles 11y ago

Does anyone know why Knuth is writing some form of C? AFAIK none of the other TAOCP contain C, or anything other than (M)MIX and pseudocode. Why change now?

JonathonW 11y ago
I haven't watched through the whole thing, but the C code I saw from skipping through looks like it's actually the output from CWEB [1], one of Knuth's literate programming tools. It combines C source code with long-form documentation, and it can either be preprocessed to TeX (to give that nice, pretty printed document that Knuth shows in the video) or to standard C source code to compile and run. CWEB is one of Knuth's languages of choice, and he's got tons of code written in it on his website [2], including versions of some of the stuff he's demoing on-screen. [1] http://www-cs-faculty.stanford.edu/~uno/cweb.html http://www-cs-faculty.stanford.edu/~uno/cweb.html [2] http://www-cs-faculty.stanford.edu/~uno/programs.html http://www-cs-faculty.stanford.edu/~uno/programs.html
kazinator 11y ago
Knuth has been using C for quite a long time now (he has not "changed now"), and it's fair to say that he likes it, based on the following: More than 20 years ago, knuth ported his literate programming system to C, resulting in CWEB. Here is a 1993 interview with Knuth about CWEB: http://tex.loria.fr/historique/interviews/knuth-clb1993.html http://tex.loria.fr/historique/interviews/knuth-clb1993.html Key quote (on the subject of C): I think C has a lot of features that are very important. The way C handles pointers, for example, was a brilliant innovation; it solved a lot of problems that we had before in data structuring and made the programs look good afterwards. C isn't the perfect language, no language is, but I think it has a lot of virtues, and you can avoid the parts you don't like. I do like C as a language, especially because it blends in with the operating system (if you're using UNIX, for example). I can only guess that Knuth doesn't use C in TAOCP because C isn't defined in the kind of way that he thinks is suitable for teaching. Every port of C to some given architecture has different parameters which effectively render it a different dialect, and there are undefined behaviors all over the place.

deleted 11y ago

[deleted]

lechevalierd3on 11y ago

For once a news headline with "Donald" not matching Trump.

nikisweeting 11y ago

I was present and unfortunately didn't understand the lecture till I looked up https://en.wikipedia.org/wiki/Huffman_coding https://en.wikipedia.org/wiki/Huffman_coding halfway through. It was very interesting after that point though!

nafizh 11y ago

Saw Donald. Thought, Not again!! Trump at hacker news too!!