
Donald Knuth's 21st Annual Christmas Lecture: Universal Commafree Codes [video] - cranium
https://www.youtube.com/watch?v=48iJx8FVuis
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weinzierl
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
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.

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Jabbles
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
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)

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nikisweeting
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!

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lechevalierd3on
For once a news headline with "Donald" not matching Trump.

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coliveira
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.

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dang
Please let's keep religious flamewars off of HN. Bikeshedding, too, while
we're at it.

~~~
gPphX
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_Le...](https://en.wikipedia.org/wiki/Royal_Institution_Christmas_Lectures)

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

