  100 prisoners and a light bulb is a long standing mathematical puzzle. The
problem was studied mostly in 2002 [5], 2003 [1], and 2004 [3]. Solutions in
published articles had average number of visits above 3850, but best solutions
on forums had (declared) average number of visits around 3500. I spent some
time in 2007-2009 to optimize the communication strategy and I pushed the
average number of visits below 3390, seems no new ideas appear after it.
Recently I have met several people familiar with published papers from
2002-2003 but not knowing newer results. Even after 2009 several papers on the
topic were published where the new results were not mentioned [4]. Whole book
was written about the problem [2]. This is why I am writing this summary.

Discrete Mathematics;History and Overview