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Questions tagged [topology]

A puzzle about disentangling knots, folding paper, separating strings and wires, and understanding the connectivity properties of elastic figures.

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4answers
161 views

Is the following topology puzzle impossible to solve? [duplicate]

There was a problem I was introduced to in grade school which my teacher claimed that not even his graduate level students could solve, and it went a little like this. You have a set of boxes in a ...
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0answers
714 views

3D ring/rope wooden puzzle (Eureka) solution?

I have a Eureka 3d Puzzle Model G: On the box there are 3 puzzles: Remove the ring Remove the rope Move the ring to the other side I have found a solution to the first puzzle: but cannot ...
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6answers
5k views

Changing baby's shirt

Baby needs a change of shirt, but baby is also sucking on a bottle (see this stock photo for a visual). If the bottle leaves baby's mouth, baby will start crying. Also, baby loves holding the ...
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6answers
1k views

Turning My Pants Inside-Out

A 12-foot long rope has two ends. One end of the rope is tied around a man's left ankle and the other end is tied around the man's right ankle. If you are not allowed to untie the rope and you're ...
6
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2answers
238 views

Teacup geometry

Inspired by the three utilities puzzle from prog_SAHIL I'm now posting a similar puzzle that makes use of the topology of a cup with a handle: The question is: How many distinct points can you ...
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2answers
1k views

The three utilities puzzle

Here is a variant of the three utilities puzzle. Famously, It is impossible to solve it on a plane paper (Euler's theorem can prove that). But can you solve it on a coffee mug? ...
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2answers
242 views

Can this be undone to make a knotless loop?

Can this be undone to make a knotless loop?
18
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11answers
6k views

IQ Test Example

I'm reading up on various IQ tests, and a slideshow that I stumbled upon gave the following example: This doesn't make sense to me, as none of the options duplicate the conditions in the far left ...
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2answers
195 views

Ant-Man in chains [closed]

"Ant-Man" is a superhero that can change his size. Usually he can get very small, but sometimes he can get large as well. In the movie 'Ant-Man' (minor spoiler here) there is a scene where he is ...
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2answers
168 views

Pulling strings…not legs?

What happens to the two strings - of the logo of G20 Summit (currently happening in Germany)-if pulled either side (in opposite directions, away from the center) at the same time ? Your options are:...
5
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2answers
768 views

Join six five-link chains to form a circular chain

Join six five-link chains to form a circular chain. To join two chains, you must cut, and then re-weld, a link. The final number of links in the circular chain will be 30. What is the minimum ...
4
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2answers
1k views

Connect the colored dots

I've got this: By connecting the dots, I get this: Could you do the same for this one: There is a unique solution. The rules are: You have to use every square, lines can't cross each other and you ...
27
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4answers
3k views

Smallest Unicode Box Drawing

What is the smallest box diagram you can draw which uses all of the Unicode box drawing characters at least once, but without leaving any loose ends? For reference, you must use each of these ...
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1answer
815 views

Ernie and the Underground Network

I haven't seen Ernie for a few weeks - he's been on holiday in the People's Republic of Kzijekistan (PRK). But yesterday I got an e-mail and thought I would share it with you. It reads as follows: ...
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2answers
570 views

Number of ways to fold a 2x4 map

M.Gardner in his book "Mathematical puzzles and diversions" states that the following 2x4 map $$ \begin{array}{|c|c|} \hline 1 & \phantom{1} & \phantom{1} & \phantom{1} \\ \hline \...
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2answers
534 views

How to generalise hang picture puzzle?

There is well known problem: The picture is attached to a string and you want to hang it on N nails so that if one takes out any of the nails, the picture falls. How do you do it? For those who ...
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5answers
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Is there a proof that a map of the United States requires 4 colors?

The Four color theorem states that no more than four colors are required for any map. Can it be proved or disproved that 3 colors can be used for United States map?
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2answers
805 views

Are there any topology puzzles similar to The Seven Bridges of Königsberg?

Leonhard Euler proved that it is impossible to solve this puzzle: The challenge is to take a walk around the area depicted, and cross each bridge (yellow) exactly once. Using topology, Euler proved ...