Seeing that such a function does not exist for the real numbers is not that hard, but what about the rationals?

Is there a function f: Q -> Q which is is strictly increasing and discontinuous everywhere on the interval [0,1]?

## Search found 17 matches

- Tue Mar 05, 2013 5:25 pm UTC
- Forum: Mathematics
- Topic: Discontinituous increasing function?
- Replies:
**20** - Views:
**3993**

- Sun May 15, 2011 12:47 am UTC
- Forum: Mathematics
- Topic: Is a random walk a sufficient model of the stock market?
- Replies:
**12** - Views:
**2731**

### Re: Is a random walk a sufficient model of the stock market?

I think 1/f noise would be a pretty accurate model.

- Tue Apr 19, 2011 9:15 pm UTC
- Forum: Mathematics
- Topic: Getting my undergrad in math. How about you?
- Replies:
**51** - Views:
**8489**

### Re: Getting my undergrad in math. How about you?

Age: 16

Education: First semester of freshman year in math done

Currently: Finishing school, no university stuff right now

I'm probably going for a minor in computer science or economics.

Education: First semester of freshman year in math done

Currently: Finishing school, no university stuff right now

I'm probably going for a minor in computer science or economics.

- Sat Apr 03, 2010 5:30 pm UTC
- Forum: Mathematics
- Topic: Self replicator pattern in Conway's Game of Life
- Replies:
**2** - Views:
**1571**

### Re: Self replicator pattern in Conway's Game of Life

It Isn't, a real replicator pattern would keep on going forever, this however stagnates after 14 generations.

- Wed Mar 03, 2010 4:59 pm UTC
- Forum: Mathematics
- Topic: Why are most mathematical constants so small?
- Replies:
**66** - Views:
**8502**

### Re: Why are most mathematical constants so small?

On the other hand, we use percentages, which esentially means mutliplying decimal fractions by 100 for no reason at all.

- Wed Feb 24, 2010 2:51 am UTC
- Forum: Mathematics
- Topic: Largest number on Twitter
- Replies:
**70** - Views:
**10616**

### Re: Largest number on Twitter

Whoops, you're right.

- Wed Feb 24, 2010 2:41 am UTC
- Forum: Mathematics
- Topic: Largest number on Twitter
- Replies:
**70** - Views:
**10616**

### Re: Largest number on Twitter

the pigeonhole principle puts the smallest untweetable number somewhere below 256^140. I don't think so. It is true that you can only define 256^140 different numbers in a tweet, but that doesn't mean the set of numbers you can define has to be convex. For example, you can define 9^9 in three chara...

- Wed Feb 10, 2010 2:00 am UTC
- Forum: Science
- Topic: public misconceptions
- Replies:
**1073** - Views:
**153129**

### Re: public misconceptions

Most people actually believe that E=mc² is the Theory of Relativity.

- Thu Jan 28, 2010 7:28 pm UTC
- Forum: Mathematics
- Topic: Everyday randomness
- Replies:
**85** - Views:
**9585**

### Re: Everyday randomness

If you really don't have access to a computer, you can use the rule 30 cellular automaton.

This should be doable on a piece of paper if you have a little time.

This should be doable on a piece of paper if you have a little time.

- Mon Jan 25, 2010 9:36 pm UTC
- Forum: Mathematics
- Topic: Everyday randomness
- Replies:
**85** - Views:
**9585**

### Re: Everyday randomness

Come, on my browser can do AES.

I think you either are overestimating the cryptographical capabilities of your Chuck or you are indeed dealing with a team of highly-skilled cryptographers with access to multi-gigaqubit-quantum-supercomputers™.

I think you either are overestimating the cryptographical capabilities of your Chuck or you are indeed dealing with a team of highly-skilled cryptographers with access to multi-gigaqubit-quantum-supercomputers™.

- Mon Jan 25, 2010 11:32 am UTC
- Forum: Mathematics
- Topic: Everyday randomness
- Replies:
**85** - Views:
**9585**

### Re: Everyday randomness

Hmm, I don't seem to understand the problem here. 1. Completely remove your computer from the Internet. There's no way anybody could find out your key now unless they have cameras watching you. 2. Generate as many random numbers in any base as you want using a CSPRNG. 3. Use them as a key for OTP en...

- Wed Jan 20, 2010 7:49 pm UTC
- Forum: Mathematics
- Topic: I'm bad at maths. Any ideas why?
- Replies:
**36** - Views:
**4599**

### Re: I'm bad at maths. Any ideas why?

I hate linear algebra, too, which I guess is mainly due to the fact that the professor I had was horrible. But honestly, if you ever dig deeper into any field of math, you will stumble upon matrices: You can use adjacency matrices for graph theory, translation matrices for analytic geometry, you can...

- Mon Nov 02, 2009 5:20 pm UTC
- Forum: Mathematics
- Topic: Max number of colors that can touch.
- Replies:
**21** - Views:
**3594**

### Re: Max number of colors that can touch.

Instead of coloring a flat plane, you could fill the surfaces of 3-dimensional objects. A torus or a möbius strip would work, they can require 7 or 6 colors respectively. A torus is also easy to represent on a 2-d screen without using 3-d graphics, just allow the player to "scroll" infinit...

- Wed Aug 26, 2009 6:23 pm UTC
- Forum: Individual XKCD Comic Threads
- Topic: 0628: "Psychic"
- Replies:
**186** - Views:
**49231**

### Re: "Psychic" Discussion

big "get out of my head randall" when i read the alt-text

- Sun Aug 23, 2009 10:13 pm UTC
- Forum: Logic Puzzles
- Topic: brain in a vat
- Replies:
**214** - Views:
**26638**

### Re: brain in a vat

As someone previously stated, the human brain also is just a kind of computer, so why could the creator of the AI not just take any human brain, attach it to a machine and call it an AI, or, even better, scan an average human brain and create a perfect emulation of it on a "normal" computer.

- Thu Jul 30, 2009 1:49 pm UTC
- Forum: Mathematics
- Topic: Continously adding digits to a number
- Replies:
**15** - Views:
**1638**

### Re: Continously adding digits to a number

Repeating 10x+3 cycles through every remainder mod 7 including 0. Q.E.D. except for 2, try it! it also cycles through all remainders mod 11 except for 7, all remainders mod 13 except for 4, all remainders mod 17 except for 11, all remainder mod 19 mod 6 ect. i checked for every prime up to 109, i d...

- Thu Jul 30, 2009 1:00 am UTC
- Forum: Mathematics
- Topic: Continously adding digits to a number
- Replies:
**15** - Views:
**1638**

### Continously adding digits to a number

I recently was told about this problem but I just can't seem to find a solution, it sounded somewhat similar to this: Starting with any natural number (which is not 0) in base 10, you keep adding digits other than 9 to the right side of it. Prove that you will always eventually get to a composite nu...