Waste less time on Facebook — follow Brilliant.
×

Dragonland.

You visit a remote desert island inhabited by one hundred very friendly dragons, all of whom have green eyes. They haven’t seen a human for many centuries and are very excited about your visit. They show you around their island and tell you all about their dragon way of life (dragons can talk, of course). They seem to be quite normal, as far as dragons go, but then you find out something rather odd. They have a rule on the island which states that if a dragon ever finds out that he/she has green eyes, then at precisely midnight on the day of this discovery, he/she must relinquish all dragon powers and transform into a long-tailed sparrow. However, there are no mirrors on the island, and they never talk about eye color, so the dragons have been living in blissful ignorance throughout the ages. Upon your departure, all the dragons get together to see you off, and in a tearful farewell you thank them for being such hospitable dragons. Then you decide to tell them something that they all already know (for each can see the colors of the eyes of the other dragons). You tell them all that at least one of them has green eyes. Then you leave, not thinking of the consequences (if any). Assuming that the dragons are (of course) infallibly logical, what happens? If something interesting does happen, what exactly is the new information that you gave the dragons?

Note by Abhishek Gupta
2 years, 10 months ago

No vote yet
1 vote

Comments

Sort by:

Top Newest

all of them will transform into sparrows on the hundredth day. Salman Khan explains it nicely in this video:http://www.khanacademy.org/math/recreational-math/puzzles/brain-teasers/v/blue-forehead-room-solution .
i think the new information given was that we told them that all the others know that all the others know that...(100 times ) at least one has a green eye Adit Mohan · 2 years, 10 months ago

Log in to reply

This is my first time go to see at here and i am really pleassant to read all at one place https://goo.gl/XTkYL1 شركة نقل عفش بالطائف https://goo.gl/A65hc1 http://goo.gl/stqjmo http://goo.gl/ZN7RMf http://goo.gl/SaoM8r http://goo.gl/Hleb36 http://goo.gl/MGNbZx http://goo.gl/x7NVgf http://goo.gl/JT3Ftl http://goo.gl/6hhaij http://goo.gl/vcAX5R http://goo.gl/hFg8a8 http://goo.gl/JdG5CL http://goo.gl/NrxLH9 http://goo.gl/wV7giL Smsma Ali · 1 year, 1 month ago

Log in to reply

http://emc-mee.com/movers-in-riyadh-company.html شركة نقل اثاث بالرياض http://emc-mee.com/transfer-furniture-taif.html شركة نقل عفش بالطائف http://emc-mee.com/transfer-furniture-tabuk.html شركة نقل عفش بتبوك http://emc-mee.com/transfer-furniture-mecca.html شركة نقل عفش بمكة http://emc-mee.com/transfer-furniture-qassim.html شركة نقل عفش بالقصيم http://emc-mee.com/transfer-furniture-khamis-mushait.html شركة نقل عفش بخميس مشيط http://emc-mee.com/transfer-furniture-jeddah.html شركة نقل عفش بجدة http://emc-mee.com/transfer-furniture-abha.html شركة نقل عفش بابها http://emc-mee.com/transfer-furniture-buraydah.html شركة نقل عفش ببريدة http://emc-mee.com/transfer-furniture-dammam.html شركة نقل عفش بالدمام http://emc-mee.com/transfer-furniture-najran.html شركة نقل عفش بنجران http://emc-mee.com/transfer-furniture-hail.html شركة نقل عفش بحائل http://emc-mee.com/transfer-furniture-alkharj.html شركة نقل عفش بالخرج http://emc-mee.com/transfer-furniture-dhahran.html شركة نقل عفش بالظهران http://emc-mee.com/transfer-furniture-almadina-almonawara.html شركة نقل عفش بالمدينة المنورة http://emc-mee.com/transfer-furniture-yanbu.html شركة نقل عفش بينبع http://goo.gl/iCBzuo شركة كشف تسربات المياه بالدمام http://emc-mee.com/water-leaks-detection-isolate-company-dammam.html شركة كشف تسربات المياه بالدمام http://goo.gl/JEQDOP شركة كشف تسربات المياه بالدمام http://emc-mee.com/transfer-furniture-kuwait.html شركة نقل عفش بالكويت http://emc-mee.com/anti-insects-company-dammam.html شركة مكافحة حشرات بالدمام http://emc-mee.com/ http://www.bssuk.net/ Smsma Ali · 1 year, 1 month ago

Log in to reply

No matter if some one searches for his required thing, therefore he/she desires to be available that in detail, so that thing is maintained over here. http://forsan-elnil.com/arabic/?id=1 شركة نقل اثاث بالدمام http://forsan-elnil.com/arabic/index.php?id=2 شركة نقل اثاث بالجبيل http://forsan-elnil.com/arabic/index.php?id=3 شركة نقل اثاث بالخبر http://forsan-elnil.com/arabic/index.php?id=5 شركة نقل اثاث بالقطيف http://forsan-elnil.com/ شركات نقل الاثاث والعفش بالدمام Smsma Ali · 1 year, 1 month ago

Log in to reply

Thanks for all your information, Website is very nice and informative content. http://goo.gl/iAJsRz شركة نقل اثاث بالدمام http://goo.gl/Vv4Sp9 http://goo.gl/52zZFy
http://goo.gl/SHZHnV http://goo.gl/qga5YC http://goo.gl/1SwlvF http://goo.gl/1kXTpJ http://goo.gl/DuLCNP http://goo.gl/iksDnr http://goo.gl/Etnu4A http://goo.gl/x3BKPU http://goo.gl/4XVcnD http://goo.gl/7VW8I5 Smsma Ali · 1 year, 1 month ago

Log in to reply

This is my first time go to see at here and i am really pleassant to read all at one place

http://www.atar-almadinah.com/khasil.html & شركة تنظيف خزانات بالمدينة المنورة http://www.atar-almadinah.com/mokafha.html & شركة مكافحة الحشرات بالمدينة المنورة http://www.atar-almadinah.com/tanzif.html & شركة تنظيف بالمدينة المنورة Smsma Ali · 1 year, 1 month ago

Log in to reply

Thanks for all your information, Website is very nice and informative content. http://www.tfa2ol.com/naklasas.html شركة نقل اثاث بالدمام http://www.tfa2ol.com/naklafsh.html شركة نقل اثاث بالجبيل http://www.tfa2ol.com/khasil.html Smsma Ali · 1 year, 1 month ago

Log in to reply

Packers and Movers in Pune @ http://www.packersmove.com/packers-and-movers-pune.php Movers and Packers in Chennai # http://www.packersmove.com/packers-and-movers-chennai.php Packers and Movers in Hyderabad @ http://www.packersmove.com/packers-and-movers-hyderabad.php Movers and Packers in Ahmedabad # http://www.packersmove.com/packers-and-movers-ahmedabad.php Ankit Singh · 1 year, 2 months ago

Log in to reply

Packers and Movers in Delhi @ http://www.11th.in/packers-and-movers-delhi.html Movers and Packers in Mumbai # http://www.11th.in/packers-and-movers-mumbai.html Packers and Movers in Noida @ http://www.11th.in/packers-and-movers-noida.html Movers and Packers in Gurgaon # http://www.11th.in/packers-and-movers-gurgaon.html Ankit Singh · 1 year, 2 months ago

Log in to reply

Offers Reliable Movers and Packers Hassle free Services in India

Packers and Movers in Chennai @ http://www.11th.in/packers-and-movers-chennai.html Packers and Movers in Noida @ http://www.11th.in/packers-and-movers-noida.html Packers and Movers in Gurgaon @ http://www.11th.in/packers-and-movers-gurgaon.html Packers and Movers in Ghaziabad @ http://www.11th.in/packers-and-movers-ghaziabad.html Packers and Movers in Faridabad @ http://www.11th.in/packers-and-movers-faridabad.html Packers and Movers in Kolkata @ http://www.11th.in/packers-and-movers-kolkata.html Packers and Movers in Bangalore @ http://www.11th.in/packers-and-movers-bangalore.html Packers and Movers in Pune @ http://www.11th.in/packers-and-movers-pune.html Packers and Movers in Delhi @ http://www.11th.in/packers-and-movers-delhi.html Packers and Movers in Mumbai @ http://www.11th.in/packers-and-movers-mumbai.html Packers and Movers in Bangalore @ http://www.11th.in/packers-and-movers-bangalore.html Packers and Movers in Ahmedabad @ http://www.11th.in/packers-and-movers-ahmedabad.html Packers and Movers in Hyderabad @ http://www.11th.in/packers-and-movers-hyderabad.html Ankit Singh · 1 year, 2 months ago

Log in to reply

Reliable Packers and Movers hassle free services in India

Packers and Movers in Delhi @ http://www.packersmove.com/packers-and-movers-delhi.php Packers Movers Mumbai @ http://www.packersmove.com/packers-and-movers-mumbai.php Packers and Movers Bangalore @ http://www.packersmove.com/packers-and-movers-bangalore.php Packers and Movers in Kolkata @ http://www.packersmove.com/packers-and-movers-kolkata.php Packers and Movers in Ghaziabad @ http://www.packersmove.com/packers-and-movers-ghaziabad.php Packers and Movers in Gurgaon @ http://www.packersmove.com/packers-and-movers-gurgaon.php Packers and Movers in Noida @ http://www.packersmove.com/packers-and-movers-noida.php Packers and Movers in Chennai @ http://www.packersmove.com/packers-and-movers-chennai.php Packers and Movers in Pune @ http://www.packersmove.com/packers-and-movers-pune.php Packers and Movers in Hyderabad @ http://www.packersmove.com/packers-and-movers-hyderabad.php Packers and Movers in Ahmedabad @ http://www.packersmove.com/packers-and-movers-ahmedabad.php Ankit Singh · 1 year, 2 months ago

Log in to reply

http://www.expert5th.in/packers-and-movers-pune/ Akash Singh · 1 year, 3 months ago

Log in to reply

http://www.expert5th.in/packers-and-movers-ghaziabad/ http://www.expert5th.in/packers-and-movers-thane/ http://www.expert5th.in/packers-and-movers-navimumbai/ Akash Singh · 1 year, 3 months ago

Log in to reply

http://www.expert5th.in/packers-and-movers-chennai/ http://www.expert5th.in/packers-and-movers-faridabad/ http://www.expert5th.in/packers-and-movers-noida/ Akash Singh · 1 year, 3 months ago

Log in to reply

http://www.expert5th.in/packers-and-movers-delhi/ http://www.expert5th.in/packers-and-movers-gurgaon/ http://www.expert5th.in/packers-and-movers-mumbai/ Akash Singh · 1 year, 3 months ago

Log in to reply

http://www.expert5th.in/packers-and-movers-pune/ http://www.expert5th.in/packers-and-movers-bangalore/ http://www.expert5th.in/packers-and-movers-hyderabad/ Akash Singh · 1 year, 3 months ago

Log in to reply

×

Problem Loading...

Note Loading...

Set Loading...