International Logic Olympiad
Logic is everywhere—whether solving puzzles, playing games, or tackling school assignments across Math, History, and English. It's also the foundation of professional fields like computer science, engineering, medicine, and law, where reasoning and problem-solving are key.
Our contest challenges students to think critically and apply logical reasoning through sets and set operations—union, intersection, complement—and symbolic mathematics at a high school algebra level. Consider the following problem:
There are four members—Abby, Bess, Cody, and Dana—with a single binary relationship: likes. The table below shows who likes whom, with a checkmark indicating that the girl in the row likes the girl in the column.
The table below describes relationships among the girls. Which of the following statements is correct?
Bess likes Dana
Dana does not like Abby
Abby likes Cody or Dana
Abby likes Cody and Dana
Abby does not like Cody nor Dana
3. Abby likes Cody or Dana
If you have a sharp mind and a passion for logical thinking, put your skills to the test and prove your reasoning in this competition!
What is the ILO?
The International Logic Olympiad is the leading logic competition hosted annually in partnership with Stanford University to promote and internationalize logic education.
Offering high school students worldwide a chance to showcase excellence in logic and problem-solving, The ILO culminates in an on-campus final round at Stanford University during the summer of 2025.
In our first year, we're proud to support:
3500+
Participants
92
Countries
2100+
Schools
2024 ILO Winners
Meet the brilliant minds who excelled in last year's International Logic Olympiad! Their dedication, problem-solving skills, and creativity set them apart on the global stage.
Want to join them next year? Start your journey today!
register now
From left to right: Zongshu Wu and Honjar Xing
Get Involved Differently
Are you interested in stepping up your involvement in the ILO? Whether you are a previous participant or brand new to the world of logic, we have plenty of ways for you to get involved. Learn more about what it means to become an ILO Ambassador below.
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