Thank you to all who expressed interest in the first announcement of the course - your interest confirmed that someone would need it.

Pavel Pasynok, thank you for agreeing to course. It’s been interesting working with you and it’s given me an incentive to finish the course and I’m particularly glad that the knowledge that you’ve learned from course has found practical application.

Alexey Kirillov, thank you very much :-) I have always been able to discuss with you any question on course. You helped me maintain my motivation and not get in a muddle. Communicating with you has inspired me to continue, especially in difficult moments. Thank you for your inspiration, positive emotions and support!

Thanks to all those who wrote comments on book - thanks to you now book not only has fewer typographical errors and typos, but also the contents of book have improved.

Thanks to all participants of online course - thanks to your questions book has become much better.

Slava Skorokhod, thank you so much for volunteering to be an editor - number of errors is now going to zero :-)