BrainDen.com - Brain Teasers

# rookie1ja

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13

1. ## Crocodile Sophism

Crocodile Sophism - Back to the Paradoxes A slim crocodile living in Nile took a child. Mother begged to give him back. The crocodile could not only talk, he was also a great sophist, and so he stated: "If you guess (Edited: predict the fate = guess correctly), what I will do with him, I will return him. However, if you don't guess his fate I'll eat him." What statement shall the mother make to save her child (what about a vicious circle ...)?

Barber Paradox (Russell's Paradox) - Back to the Paradoxes Analogue paradox to the paradox of liar formulated English logician, philosopher and mathematician Bertrand Russell. There was a barber in a village, who promised to shave everybody, who does not shave himself (or herself). Can the barber shave himself and keep the mentioned promise? Edited (better wording?): In a village, the barber shaves everyone who does not shave himself/herself, but no one else. Who shaves the barber?
3. ## What is better - eternal bliss or a simple bread?

What is better - eternal bliss or a simple bread? - Back to the Paradoxes What is better than eternal bliss? Nothing. But a slice of bread is better than nothing. So slice of bread is more than eternal bliss.
4. ## Double Liar Paradox (Jourdain's paradox)

Double Liar Paradox (Jourdain's paradox) - Back to the Paradoxes This version of the famous paradox was presented by an English mathematician P. E. B. Jourdain in 1913. The following inscriptions are on a paper: Back side Inscription on the other side is true Face side Inscription on the other side is not true
5. ## Lazy-bones Paradox

Lazy-bones Paradox - Back to the Paradoxes If destiny designed a master plan, which defines everything that is to happen, isn't it useless to for example go to a doctor? If I am ill and it is my destiny to regain health, than I will regain health whether I visit a doctor or I don't. And if I shall not be healthy again, than I will not with or without help. If I am ill and destiny has a definite plan for me, than it is useless to go anywhere. How could you question the presented opinion?
6. ## Think about these

Think about these - Back to the Paradoxes 1. Let's say (hypothetically) there is a bullet, which can shoot through any barrier. Let's say there is also an absolutely bullet-proof armour, and nothing gets through it. What will happen, if such bullet hits such armour? 2. Can a man drown in the fountain of eternal life? 3. Your mission is to not accept the mission. Do you accept? 4. This girl goes into the past and kills her Grandmother. Since her Grandmother is dead the girl was never born, if she was never born she never killed her grandmother and she was born. 5. If the temperature this morning is 0 degrees and the Weather Channel says, "it will be twice as cold tomorrow,".... What will the temperature be? 6. Answer truthfully (yes or no) to the following question: Will the next word you say be no? 7. What happens if you are in a car going the speed of light and you turn your headlights on? 8. I conclude with this challenge: Let the God Almighty create a stone, which he can not pick up (is not capable of lifting)!
7. ## Is it possible to give what we don't have?

Is it possible to give what we don't have? - Back to the Paradoxes Sophist: "Yes. Greedy man gives his cash with sorrow. However, he doesn't have the cash with sorrow, so he gives what he doesn't have."
8. ## Liar Paradox (Eubulid or Epimenides Paradox)

Liar Paradox (Eubulid or Epimenides Paradox) - Back to the Paradoxes This is a well known paradox written by the great stoical logician Chrysippos. The poet, grammarian and critic Philetus of Cos was said to have died of exhaustion attempting to resolve it. 1st problem: A Cretan sails to Greece and says to some Greek men who are standing upon the shore: "All Cretans are liars." Is he lying or telling the truth? 2nd problem: Read after resolving the first as this contains a massive hint. 2. Now assume that either all Cretans are liars or all Cretans tell the truth. A Cretan states "All Cretans are liars and all I say is the truth." Is he lying or telling the truth? If someone says "I always lie", are they telling the truth? Or are they lying? Rational assumptions: A liar always tells lies, and a truth-teller always tells the truth. If a person is not a liar, then they are a truth-teller, and vice versa. This Cretan is not the only Cretan. The two problems are of disjoint cases. Resolution Examples of incorrect interpretations from replying posts This is an attempt to find a loophole in the wording, which is not an objective response to a logic problem. If you're going to make a semantic argument, you might as well state that words are not universally meaningful. You could be right, but this is no fun and detracts from the idea of a paradox (or really, anything...). It IS a paradox (the word is just a descriptive label), even if it is not 'truly paradoxical'. Note that this thread is closed since there have been hundreds of posts and resolution is summarized in this very first post.
9. ## Submit New Optical Illusions

Have you come across a beautiful illusion on the web? Share it here: 1. create account in these BrainDen forums 2. start new topic in this Illusions subforum 3. attach your illusion picture in your topic Have you seen our whole collection of optical illusions yet?

11. ## Spoiler help

Enter the spoiler code manually - copy or write this [spoiler='visible title']hidden text[/spoiler]
12. ## What color is this dress?

That's a great optical illusion which got viral 2 days ago and it divided internet population to 2 groups - those who saw "white and gold" and those who saw "blue and black" (who were in minority). Even many celebrities got involved. Of course, what might see as white is actually blue. It was quite well explained on many sites already. Since I have here a nice collection of color illusions as well, BrainDen was quoted in several articles about that dress (Washington Post, Guardian etc.). Thanks for sharing the illusion. Keep them coming. Enjoy the Den
13. ## What Are Your Favorite BrainDen Puzzles

Are you new to BrainDen and you want to see the best brain teasers? There are thousands of puzzles and riddles here. This thread is a place where you can post your 3 most favorite puzzles published on this site. You can add a short reason why you like them too. All great puzzles deserve due attention. Don't let great puzzles posted a year ago be unnoticed. Let me start with my favorites. Hats On A Death Row - simple conditions yet so hard and can be solved without deep knowledge of math (over 500,000 views) Honestants and Swindlecants III - great example of logic operations Weighing Puzzle IV - I read this puzzle in year 2002 (I think) and it was one of the reasons to start this whole site Post links to 3 puzzles that you consider the best. And remember, solution is already posted - DO NOT resurrect these old threads. Enjoy BD
14. ## Can't see the trick?

Don't you know what to look for in the illusions published on my page (eg. Visual Illusions or Optical Illusions)? Attach here the one you would like know the trick for and I will give you a hint.
15. ## The Coup of Rhotus Mafia Signups

Site Admin is happy to help and unleash epic BrainDen Mafia battles of wits again. I have invited 17 old Mafia players via mail.
16. ## â€‹ Symbols appearing when editing

Thanks for reporting the issue. Sorry it took so long but it should be corrected now. Let me know if there is anything else that could be improved.
17. ## Farewell to SuperPrismatic

With great sadness in my heart I have learnt that SuperPrismatic, our well-respected forum moderator, has died suddenly on March 25th 2014 at the age of 69. It was a heart attack without any previous medical problems. Michael (whom we knew as SuperPrismatic) left a wife and 5 children. He joined BrainDen Brain Teaser Forums 6 years ago and his genius was apparent from the very beginning. However, he was not only brilliant but also very respectful which is also why I offered him to be The Moderator here. It was an honor for me that he accepted my offer and that he contributed to this website so much. SP's daughter wrote us that SP enjoyed this BrainDen website and SP wouldn't want to abandon this place without saying Farewell. And that's why let me use this thread to: 1. thank SP for all the great discussions, all the posts where he helped others and all the time he spent here with us 2. share my sincere condolences with SP's family Please join me in this Last Farewell to SP. Thanks.
18. ## Mafia Video Game - Town of Salem

That's great news. I wish you all the best
19. ## Chinese translation issue

Hi Wing, thanks a lot for pointing that out. I have corrected the wording as per your suggestion and you can check it here (you might need to refresh the page in your browser to see the change) - http://brainden.com/logic-puzzles.htm If you notice anything else that could be improved, don't hesitate to let me know and I will do my best to improve it. Thanks.
20. ## help with searching

Not sure if I understand. Keywords should already be included in the original puzzle threads and adding keywords which are not already part of the original thread would still leave some synonyms out. Any example where you searched for some old thread and could not find it by using some specific keyword?
21. ## My goodness, there's a...

Yes, BrainDen website (both forum and non-forum part) should be optimized for mobile as well. What is your experience? Do you like it?
22. ## Posts and Titles

That's correct Let me know if you want to know further details or if you have any suggestions to improve anything.
23. ## BrainDen Brain Teasers Android App

Great news for all who have Android mobile phones. You can enjoy the classic brain teasers which started the whole site in a very simple application. Check out the following Google Play page, from where you can download the app. It's not only in Slovak but also in English language - you can switch between both in the app easily. Enjoy and let me know your comments. Sample screen:
24. ## A few sentences from life

A few sentences from life - Back to the Paradoxes 1. Nobody goes to that restaurant, because it is too crowded. 2. Don't go near the water, till you have learned how to swim. 3. The man who wrote such a stupid sentence, can not write at all. 4. If you get this message, call me, and if you don't get it, don't call. 5. ADVERTISEMENT: Are you an analphabet? Write a letter and we will send you free of charge instructions how to undo it.
25. ## Time

test 17:03 CET - time corrected (10 minute delta) If you see 1 hour difference then you may change your daylight saving settings. Let me know how it goes.
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