I'm using some codes that I modified, from Paradigms of Artificial Intelligence Programming to create another project, the project is released under GPL V2.

The License agreement is written here, it says: Copyright © 1998-2002 by Peter Norvig.

My question is: Were's almost in 2014, do I still have to include that license or did it expire and therefore I may use the codes anyway that I like?


3 Answers 3


Copyright generally does not expire until 50 or 70 years after the death of the person who wrote it.

Therefore, you must still license your own project under the GPL v2.

  • Now, standard IA!aL disclaimers apply, yada yada.
    – Joe Z.
    Dec 11, 2013 at 0:01

The copyright line doesn't refer to the code, but to the license itself. The time span does not determine until when the copyright is active, but during which time span the copyrighted subject was created and/or modified. This is not relevant here.

You are not free to use the code in any way you like: You have to adhere to the license which you linked to:

  • The origin of this software must not be misrepresented, either by explicit claim or by omission.” – I would interpret this such that you would have to mark the sections in your source code taken from Mr. Norvig. Omitting any credit to him would be a misrepresenting the origin of your software by omission.
  • Altered versions must be plainly marked as such, and must not be misrepresented as being the original software. Altered versions may be distributed in packages under other licenses (such as the GNU license).” – If you alter the code (which you intend you do), you may distribute the altered version under any license you choose. However, you are not allowed to present the altered version as if it were written by Mr. Norvig.

In addition to marking the section of code which are based on Mr. Norvigs work, I would think crediting him with a sentence like

Parts of this software are based on code from Paradigms of Artificial Intelligence Programming by Peter Norvig. See <http://norvig.com/paip.html>.

in your copyright statement would be appropriate.

I am not a lawyer, so you should really consider seeing one.


As with all legal questions - you really should ask a lawyer.

But a short answer: the date in the copyright is when changes were made by that author, not any indication of copyright expiry. The original author worked on the code between 1998 and 2002 - those changes are still under copyright, and will be for a some while longer.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.