[Retros] Invisible King

[Mario Richter]

> Here is one short paper on the Invisible King genre in chess composition:

> http://chessproblem.net/viewtopic.php?f=13&t=371


For those, who are interested in the mathematical background
(and who are able to understand russian texts), there is also
available the following E-paper:

Search under counteraction 
V. Yu. Andrianov, N.N.Petrov 

www.mathnet.ru/php/archive.phtml?wshow=paper&paperid=165&option_lang=eng

Best regards,

  mario