# Overview

On this site you will find

## iPhone/iPad/iPod touch Apps

Information- and help page for various iPhone/iPad/iPod touch apps such as BetterBrain, iDungeon, iAltairHD and Tinnitus Music Player.

## AltairZ80 Simulator

Download pages for the AltairZ80 simulator which works on Windows, Macintosh, Linux and Zaurus. Also there is rich collection of operating systems including CP/M, programming languages such as Basic, C, Pascal, and application programs (e.g. WordStar and MultiPlan) ready to run on the simulator.

## XYZ GeoBench

Download the XYZ GeoBench for Macintosh including Object Pascal source code. The GeoBench is an interactive system featuring algorithm animation for geometric computation.

# Other Interests

You can find pictures and information about our travels on Verena's home page. If you are interested in Swiss German (Schweizerdeutsch) have a look at www.schweizerdeutsch.info.

# Prime Proof

Proof of Peter Schorn: Assume there exist only *m* prime numbers.

Let *n* = *m* + 1.
For two numbers *i* and *j* with 1 ≤ *i* < *j* ≤ *n*, then

*n*!)

*i*+ 1, (

*n*!)

*j*+ 1 ] = 1.

Indeed, *j* = *i* + *d*, with 1 ≤ *d* < *n*, so

*n*!)

*i*+ 1, (

*n*!)

*j*+ 1 ] = gcd[ (

*n*!)

*i*+ 1, (

*n*!)

*d*] = 1.

Therefore the *n* integers (*n*!)*i* + 1 (for *i* = 1, 2, …, *n*) are pairwise relatively prime.
If *p*_{i} is a prime dividing (*n*!)*i* + 1, then *p*_{1}, *p*_{2},
…, *p*_{n}
are distinct primes with *n* = *m* + 1, which is a contradiction
[Paulo Ribenboim, The New Book of Prime Number Records, p. 5, Springer-Verlag 1996, 3^{rd} edition].