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No part of this website may be reprinted or reproduced or utilized in any form or by any electronic, mechanical or other means, now known or hereafter invented, including, phototcrypting and recording, or in any information storage or retrieval system, without permission in writing from the publisher.

© 1999-2010 Jürgen Köller 

Hello, this also is a place to introduce myself a little. 

Several email writers wanted to know whether I am a lazy student who doesn't finish his studying. This is a nice idea.

I was a teacher of mathematics and physics at a high school (German: Gymnasium) up to summer 2000. Now I am retired. Maybe people of my age solve crossword puzzles. I create web sites. I work on topics of the recreational mathematics with great pleasure. I had no time to do so as an active teacher. Sometimes I am astonished how many pages have already been assembled. 

This also is a place to say thank you for the emails I have received since 1999.
Thank you!