# Can You Solve The Friendship Riddle?

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## Description

In a group of 6 people, you might find that some people are friends on Facebook, or you might find out that no one is friends on Facebook. Show that there is always a group of 3 people in which either: (a) all 3 people are mutual friends or (b) the 3 people are mutual strangers (no one is friends on Facebook). The video presents a solution to this problem which is also known as the Friendship Theorem and is an example of Ramsey Theory (a field which studies the conditions in which order arises).

Blog post: http://wp.me/p6aMk-4Ks

Ramsey Theory Friendship Theorem references

https://plus.maths.org/content/friends-and-strangers

https://en.wikipedia.org/wiki/Theorem_on_friends_and_strangers

http://mathgardenblog.blogspot.com/2012/12/Ramsey33.html

If you like my videos, you can support me at Patreon: http://www.patreon.com/mindyourdecisions

Connect on social media. I update each site when I have a new video or blog post, so you can follow me on whichever method is most convenient for you.

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My Books

"The Joy of Game Theory" shows how you can use math to out-think your competition. (rated 4/5 stars on 23 reviews) http://amzn.to/1uQvA20

"The Irrationality Illusion: How To Make Smart Decisions And Overcome Bias" is a handbook that explains the many ways we are biased about decision-making and offers techniques to make smart decisions. http://amzn.to/1o3FaAg

"Math Puzzles Volume 1" features classic brain teasers and riddles with complete solutions for problems in counting, geometry, probability, and game theory. Volume 1 is rated 4.5/5 stars on 11 reviews. http://amzn.to/1GhUUSH

"Math Puzzles Volume 2" is a sequel book with more great problems. http://amzn.to/1NKbyCs

"Math Puzzles Volume 3" is the third in the series. http://amzn.to/1NKbGlp

"40 Paradoxes in Logic, Probability, and Game Theory" contains thought-provoking and counter-intuitive results. (rated 4.9/5 stars on 7 reviews) http://amzn.to/1LOCI4U

"The Best Mental Math Tricks" teaches how you can look like a math genius by solving problems in your head (rated 4.7/5 stars on 3 reviews) http://amzn.to/18maAdo

"Multiply Numbers By Drawing Lines" This book is a reference guide for my video that has over 1 million views on a geometric method to multiply numbers. http://amzn.to/XRm7M4

Blog post: http://wp.me/p6aMk-4Ks

Ramsey Theory Friendship Theorem references

https://plus.maths.org/content/friends-and-strangers

https://en.wikipedia.org/wiki/Theorem_on_friends_and_strangers

http://mathgardenblog.blogspot.com/2012/12/Ramsey33.html

If you like my videos, you can support me at Patreon: http://www.patreon.com/mindyourdecisions

Connect on social media. I update each site when I have a new video or blog post, so you can follow me on whichever method is most convenient for you.

My Blog: http://mindyourdecisions.com/blog/

Twitter: http://twitter.com/preshtalwalkar

Facebook: https://www.facebook.com/pages/Mind-Your-Decisions/168446714965

Google+: https://plus.google.com/108336608566588374147/posts

Pinterest: https://www.pinterest.com/preshtalwalkar/

Tumblr: http://preshtalwalkar.tumblr.com/

Instagram: https://instagram.com/preshtalwalkar/

Patreon: http://www.patreon.com/mindyourdecisions

Newsletter (sent about 2 times a year): http://eepurl.com/KvS0r

My Books

"The Joy of Game Theory" shows how you can use math to out-think your competition. (rated 4/5 stars on 23 reviews) http://amzn.to/1uQvA20

"The Irrationality Illusion: How To Make Smart Decisions And Overcome Bias" is a handbook that explains the many ways we are biased about decision-making and offers techniques to make smart decisions. http://amzn.to/1o3FaAg

"Math Puzzles Volume 1" features classic brain teasers and riddles with complete solutions for problems in counting, geometry, probability, and game theory. Volume 1 is rated 4.5/5 stars on 11 reviews. http://amzn.to/1GhUUSH

"Math Puzzles Volume 2" is a sequel book with more great problems. http://amzn.to/1NKbyCs

"Math Puzzles Volume 3" is the third in the series. http://amzn.to/1NKbGlp

"40 Paradoxes in Logic, Probability, and Game Theory" contains thought-provoking and counter-intuitive results. (rated 4.9/5 stars on 7 reviews) http://amzn.to/1LOCI4U

"The Best Mental Math Tricks" teaches how you can look like a math genius by solving problems in your head (rated 4.7/5 stars on 3 reviews) http://amzn.to/18maAdo

"Multiply Numbers By Drawing Lines" This book is a reference guide for my video that has over 1 million views on a geometric method to multiply numbers. http://amzn.to/XRm7M4

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