To Bloody Go...

On a small planet not far away lived a strange race. A long time ago all the members of that species had one of three eye colors: blue, green or brown. In some point in history a famous war took place, initiated by the blue and brown eye faction. They genocided all green eyes, thus eliminating the green eye color from their race, and reducing the population of the planet to a few hundred. Soon after that war the factions were disbanded, and eye color was from that point on considered an inappropriate topic. Some rules were later established for the benefit of the whole society, so that something like this could never, ever happen again. The rules were as follows:

1. Nobody is allowed to talk about eyecolors.
2. If anyone gets to know his own eyecolor he must commit suicide at midnight in the town square.

Now I must explain the way this species was thinking, so you understand their reactions later on. You must understand that they all were really strict about those rules. In the beginning some people happened to accidently see their eyecolor in some reflective surface or puddle of water, and every last one of them faithfully comitted suicide the night after. After a few incidences all mirroring surfaces were removed from the cities, to minimize the risk. Also, this species was a very logical thinking. Although they still lacked knowledge in some areas, they thought clearly and logically, and trusted in the results they got, even if it led to their own death. Last, the way it worked after the rules were established was that everyone knew the eyecolor of everyone else on the planet, but not his own. Of course, on a small planet like this, they all saw everyone everyday, so a suicide was immediately noted.
Well, the people on this little planet were living for a few hundred years in peace and harmony, when something bad happened:

A little spacecraft crashed down in the desert near one of the large cities, leaving a big crater. Immediately the friendly people tried to rescue the astronauts, but it was too late. The only thing they recovered from the craft was a book about mathematics. In the same night a big meeting was called on, and everyone came together in a large hall. The book was read to the whole population, because it offered new concepts that were so impressive and striking that everyone had to know about them. But, knowledge isn't always a good thing. The knowledge in that book made the people aware of facts they didnt know about before, and made them realize a few things. In the following nights everyone was really nervous.

Then, in the 250th night after the dreaded meeting, all brown eyes committed suicide, thus eliminating the whole species, and leaving the planet an empty brick in the wide universe.

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Blue eyes present during the meeting:
Number of nights in which suicides happened:
Are there more blue or brown eyes in the meeting?
Which mathematical concept made them kill themselves?