71
votes
Accepted
Changing baby's shirt
Step 1:
Step 2:
Step 3:
Step 4:
Answer from an experienced and sympathetic father of 3.
- 4,364
55
votes
34
votes
Changing baby's shirt
Follow Steps 1 and 2 of Pugmonky's solution. Then
Step 3
Step 4
Step 5
Please don't try this at home...
- 14.1k
31
votes
Accepted
IQ Test Example
The explanation in the slide seemed very odd, so I Google Image searched "culture fair IQ topology" and lots of variations of this image came up:
If you look at the topology question, it matches the ...
- 21.8k
17
votes
Accepted
The three utilities puzzle
When trying to connect all utilities $A$, $B$ and $C$ to the three houses one realizes that
And this is how it looks like on a cup:
- 5,948
15
votes
Accepted
Turning My Pants Inside-Out
Ok, having racked my brain on this for quite some time, I’ve come to the conclusion that if you don’t employ any underhanded tactics, it’s utterly
to invert the pants.
To see why this is, notice ...
- 80k
15
votes
Accepted
A (not so) K₁₂ problem
Here it is:
Explanation...
What is that?
Which properties it have?
Details about topology
Why are the holes' neighbourhoods so complicated?
A naive attempt to join many regions inside a hole would ...
- 10k
13
votes
Accepted
It boggles my mind
The hidden 5-letter word is:
The way to find this is first to note that what we are looking at is...
Now we look at the first grid and notice...
So let's get to work. I spotted a few real words at ...
- 155k
13
votes
Accepted
Bridge in a walled garden
Here's one way it can be done:
The three gray paths are the new ones that pairwise-connect A-C, C-E, and E-A.
- 151k
12
votes
IQ Test Example
I believe ffao is correct about the image being a mistake, however we're then left with 'what is the solution to the original image?'
I think I figured it out...
Misdirection, making us assume image ...
- 961
12
votes
Accepted
Drawing a complete graph of 5 nodes on a torus
Here is a picture of the 5 graph:
A flat version (perodic boundaries) is easier to digest and reveals the fundamental symmetries:
and of the 6 graph:
and the 7 graph:
Flat version (perodic ...
- 10.4k
12
votes
11
votes
Accepted
Can this be undone to make a knotless loop?
Answer:
Explanation:
In general, proving a knot is not the trivial knot is a very nontrivial task (no more knot/not puns, I promise!). The general strategy is to find some property of the knot that ...
- 32.8k
11
votes
Accepted
Connecting 6 dots with 6 curves
A solution with symmetry. Six endpoints and nine intersections (no tangents):
- 17k
11
votes
Accepted
Are three colors sufficient to color a map with convex regions?
Not necessarily - consider any such map featuring a triangular region, where each of the three neighbouring regions borders each of the others. These four regions all touch each other so must all be ...
- 2,170
10
votes
Teacup geometry
Deusovi has already shown why the answer must be what it is, but there's one thing that can still be added to the answer. That is, actually drawing this many points on an actual cup. While I've ...
- 2,676
10
votes
Drawing a complete graph of 5 nodes on a torus
Start with this 'snowflake' pattern:
So, we can do it like this:
There's another way to look at it that's based off:
- 151k
10
votes
Accepted
9
votes
Drawing a complete graph of 5 nodes on a torus
Since the surface of a donut (or toroid) is topologically equivalent to a rectangular space with both pairs of edges wrapping, we can represent a toroidal embedding of a graph as such (which is also ...
- 17.1k
9
votes
Are three colors sufficient to color a map with convex regions?
Three colours won't be enough for all maps.
Here's one troublesome map made of 6 rectangles. (EDIT: graphics cleaned up. Also, the rectangles are now squares.)
- 80k
8
votes
IQ Test Example
Most likely:
There has been a mistake.
Oh, the irony...
There are several things wrong here:
Grammatical errors:
It says '5 choices provided' and there are 6, if we assume that the box furthest ...
- 64.9k
8
votes
8
votes
Two arcs equal three arcs
Here's one solution. See this album for larger images. The multiset sum of the two arcs on the left, when placed on top of each other, equals the multiset sum of the three arcs on the right when ...
- 541
8
votes
Accepted
How can the man remove the string loop hanging from his right hand?
Since OP says they have seen the solution (of which they are actually a couple that only differ in minor details), but have trouble understanding it, here's my go at explaining what's going on.
In ...
- 80k
7
votes
7
votes
Accepted
Teacup geometry
This is topologically equivalent to a torus, and you can go up to 7 points:
as shown by this Math.SE answer.
The diagram for this could look for example like this:
One can also just look up the ...
7
votes
IQ Test Example
This has a very logical explanation. You must follow the example in the left most box as to where to place the dot in the subsequent examples
The dot must fall inside a circle, and outside of the box
...
- 1,355
7
votes
Connecting 6 dots with 6 curves
Here's something:
Alternatively, if you actually need connectedness,
- 13.2k
7
votes
Accepted
Toroidal tic-tac-toe
The first player
On the torus, every pair of points extends to a line of three. And up to symmetry, the first move can be assumed to be the center, and the second move is then either an edge or ...
- 796
6
votes
Accepted
How to use a Mobius strip for puzzle creation?
Here's one:
HAISU with a twist
and another:
https://patents.google.com/patent/US5324037A/en
A completed, solved game puzzle 10 is a mobius strip made of multiple columns 24 and rows 22 of blocks ...
- 35.7k
Only top scored, non community-wiki answers of a minimum length are eligible