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Questions tagged [proof-without-words]

A puzzle asking about a proof (usually mathematical) expressed with diagrams and without words.

16
votes
3answers
2k views

Four buttons on a table

I was asked lately (in an interview) to solve this puzzle, which is similar to the 4 cups on table puzzle. In a certain room there is a rotating round table, with 4 symmetrically located ...
7
votes
1answer
173 views

Proof by induction without words

This seems more like a proof about induction than a proof by induction.   But what is this proof really about? That is, what circuit with an inductance of 4 henries between A and B does that ...
9
votes
2answers
425 views

A big logical mess

I found a drawing under a stack of books in my house. It looked like a logical circuit diagram, so I decided to make it. I assumed that I was allowed to put anything in the boxes with the question ...
8
votes
1answer
641 views

There oughta be a law without words

There really oughta be a law. There really is! $\require{begingroup}\begingroup \small\sf \def \& { & \kern-.5em = \kern-.5em & } \def \l #1 / #2 { \log \frac {\normalsize #1} {...
5
votes
1answer
168 views

A strange traffic light

I saw a mysterious picture on an electronic whiteboard in a school I was walking past. I couldn't hear what the teacher was saying, but I could see on the timetable that it said 'Maths'. Can you work ...
6
votes
1answer
354 views

Some day in the park with Fiqo

   “Awwwwhat a cute little diagram,” the stranger said, “what’s its name?”    “Fi qo.   (A ...
11
votes
4answers
1k views

A line in Connect Four

When I was young, I was playing with a friend. Of course, the topic soon turned to mathematics (as it always does), and we got into an argument over something. We went on for some time, then he got ...
7
votes
1answer
159 views

Proof without curves

  Say, what’s that in the distance?   Could be a road full of cars or a wire full of electricity, or whatnot, but this much is for sure:    It is straight and infinitely ...
11
votes
2answers
752 views

What the L are they trying to prove?

Seems some L t rominoes have developed a punk attitude and feel they have something to prove because people always play with dominoes instead.   They are even jealous of I trominoes, who ...