Error Correction & International Book Codes - Computerphile

Moving on from crude error correction to more sophisticated methods, Professor Brailsford demostrates using the ISBN 'book code'.

Reed Solomon Codes: COMING SOON

This video was filmed and edited by Sean Riley.

[dqq]

My father is a very proper mathematician and I've always lived in his dismissal of discrete mathematics. I'm now a CS guy, thanks for sharing the fascination and inspiration to not be dismissive!

[stoneskull]

Professor Brailsford is like the computer Santa. So patient and good-humoured. terrific to listen to. Man, I love computerphile.

[gordonrichardson]

And the book title is ISBN 0201135027 - Theory of Information and Coding by Robert Mceliece.

[whatsrm]

Such a joy watching the prof speak so passionately!

[tamasdemjen]

Galois practically revolutionized mathematics while he was a teenager. He solved a polynomial root problem standing for 350 years, and laid the foundations for abstract algebra. Imagine what he could've done had he lived a few decades longer. His last words: Don't cry, Alfred! I need all my courage to die at twenty!

[adityasriram]

I am extremely intrigued by what Dr. Brailsford mentioned towards the end about Galois Theory. Has this been covered in some video already ? If not is it possible to make a video about the same ?

[harrysvensson]

Will you ever cover CRC (CyclicRedundancy Check)?
It would be interesting to hear how the polynomials work, because I've never understood what makes one polynomial better than another.

Is Hadamard Codes coming too?

[nab-rkob]

Little Feat! Spelled it right the first time. I laughed at the beginning when he was discussing picking the right number to do the test with. I do the same thing when trying to figure out how many characters my password length will be.

[jeremiahmullikin]

I am very fortunate to have viewed this.

[superscatboy]

"Prime numbers, as we know, are completely magic"

[sonicthehedgehog]

What a coincidence, I haven't watched Computerphile in a while because I was busy trying to get Reed-Solomon codes to work in C#, after many failed attempts I pretty much succeeded this time, and guess what got uploaded? another video on error correction!
_Sees end of the video and the description_
What?! after so many videos on error correction they finally are going to do it. Reed-Solomon codes!

[JNCressey]

2:43 "I'm going to be talking about integers but including zero at the bottom end."
Integers actually include the negative numbers also. The phrasing of 'zero at the bottom end' and omission of mentioning negatives makes it sound like the set being described is the natural numbers. However, the set of natural numbers fails even sooner in the following steps since it does not contain additive inverses.

[creature_of_fur]

Amazing! I've never been able to tackle the Reed-Solomon EC, but now that video is a pretty solid background. Can't wait for the Reed-Solomon video!

[CathyInBlue]

Only ISBN-10 (10 digits) is modulo 11. ISBN-13 is modulo 10. A snag with modulo 11 arithmetic is your get not only 0-9, but 10. How do you represent 10 in a single (check) character? They chose the letter X. I suppose because it looks like the Roman numeral for 10. So, that is why when you are looking at a lot of 10 digit ISBNs, some of them end in the check digit of X. A 13 digit ISBN will never terminate in an X, because modulo 10 is sane in a decimal number system.

Also, if the math of an ISBN doesn't work out properly, it doesn't actually give you any information as to WHICH digit (of 10 or 13) is wrong. It could even be the check digit itself that's wrong. It just tells you that there's SOMETHING wrong with those ISBN digits. Which one? No way of telling.

[MrHkrammes]

Great class! I only miss the last video on the series, as it seems not to be available on youtube yet :(

[blahfasel]

The hyphens in the ISBN aren't arbitrary, for the old ISBN-10 system they separate the number into four blocks, the group number (1 to 5 digits, mostly a country code, but for some languages widely spoken in multiple countries there is a language code instead, for example 0 or 1 for English, and countries where those languages are primarily spoken generally don't have their own country code, so there isn't for example a code for the UK or the US), the publisher number (1 to 7 digits, assigned by regional organisations, publishers can have multiple codes if they exceed their initial assignment, or through acquisitions for example), the title number (1 to 7 digits, assigned by the publisher), and finally the check digit. The length of the different blocks of course always has to add up to 10, so you can't have for example a 3 digit group number and a 6 digit published number, as that would leave no room for the title number.

For the new ISBN-13 the division is mostly the same, except that there is a new prefix added at the front which is (at the moment) either 978 or 979. The 978 prefix encompasses all the old ISBN-10s, you simply add the prefix in front of the old ISBN and replace the check digit with a EAN-13 check digit instead (this corresponds to the old "bookland" encoding of ISBNs into EAN-13 barcodes). The only group numbers with a 979 prefix currently allocated are "979-10" for French (the language, not France as a country!), "979-11" for South Korea (this is a country, not a language code), and "979-12" for Italy (however also used for italian language books published in Switzerland)

[colinstu]

15:43 what's that CD jewel case seen to the right of the lamp / left of the monitor?

[lawrencedoliveiro]

I’ve wondered why telephone numbers don’t have check digits. It would reduce the incidence of wrong numbers by 90%. Yes, it would make them longer. That mattered more back when they might only have been 5-6 digits. Now that they are commonly 7-8 digits or longer (particularly for mobile phone users), it seems less of an issue.

Come to think of it, why are we still using telephone numbers? They’re an idea that dates from the 19th century. Why don’t we use 20th century Internet-based technologies, such as the Domain Name System? Use names, instead of numbers, to connect to people.

[SebastiaanDingemans]

1:17 international standard book numbers book codes

[sonicthehedgehog]

Is that Reed-Solomon video still coming? or does it only exist in the same dimension as that one Numberphile2 "The Moving Sofa Problem" video?

Edit: That Reed-Solomon video finally came after 1 1/2 months.