North American Computational Linguistics Open

NACLO at Yale

Are you a student with a knack for languages, logic and computational thinking? Would you like to try your hand at deciphering an ancient script or deducing the logical patterns of Swahili or Hawaiian? If so, then you should participate in NACLO!

What is NACLO?

NACLO stands for the North American Computational Linguistics Open competition. It is a contest for high school and middle school students in which they are asked to solve linguistics problems drawn from a variety of languages. Only logic and reasoning skills are necessary; no prior knowledge of particular languages or linguistics is required.

Since 2013, Yale University has been serving as a local site for NACLO, which meant that students have been able to attend trainig sessions and participate in the competition on Yale’s campus. This academic year (2023-24), there will be two rounds of competition: a first (Open) round on Thursday, January 25th and a second (Invitational) round, on March 14th, for students who perform exceptionally well in the Open round. We expect that we will be allowed to host them in person again at Yale. 

Training Sessions

The Yale Department of Linguistics hosts training sessions to provide information about NACLO and to allow students to try out practice problems. The sessions will take place between 2:00pm and 4:00pm on the following Sundays: October 15, November 5, November 26, 2023, and January 21, 2024. If you plan to attend these sessions, please register using this link.  If you have any questions about these training sessions, or about the NACLO contest at Yale, send email to Prof. Raffaella Zanuttini at

Contest Information

At the NACLO website, you can find information about the competition including practice problems and registration informationFor information on this year’s  contest at Yale, see the Contest Info page. 

Sample question: Cat and Mouse Story

“Okay, so my cat pombled gwee the trowby, and she pombled gwee the foba. She pombled ippip the foba and pombled gorch the foba, and eventually she pombled ippip the trowby.”

Your friend has apparently joined some strange new subculture and is trying out the slang. Either that or he hit his head. Whatever the cause, it looks like your friend has replaced the words down, into, up, run, mouse, and street with the words gwee, ippip, trowby, foba, pomble, and gorch. You can’t yet tell which is which, so you have this conversation:

You: So, it started off with the cat pombling the trowby gwee.
Him: That’s nonsense; that’s not even a good sentence.
You: Could I say “The cat pombled the foba gwee?”
Him: That’s just as bad.
You: It was gwee the foba that the cat pombled, right?
Him: Correct.
You: Then the cat pombled gorch the foba and ippip the foba.
Him: Yes.
You: And the cat pombled gorch the foba and ippip the trowby?
Him: You’re talking nonsense again.
You: But it was ippip the trowby that the cat pombled?
Him: You don’t know how to use words, do you?
You: The cat pombled the trowby ippip.
Him: That sounds a lot better.

What do the following words mean? Context clues are useful to give you hints, but to prove which words mean which, you should also use your friend’s judgments about your attempted sentences.


Visit the NACLO website to find the answers and more practice questions.