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Define semiregular polygon as a polygon which has all of its' edges of the same length. Also, all of its' interior or exterior angles must be equal (meaning that any interior angle must be x or 360-x). It must be concave and simple (it should not self-intersect) and only two of its' edges are allowed to meet in each corner. Find the semiregular polygon that has the minimum number of edges.

With great sadness in my heart I have learnt that SuperPrismatic, our well-respected forum moderator, has died suddenly on March 25th 2014 at the age of 69. It was a heart attack without any previous medical problems. Michael (whom we knew as SuperPrismatic) left a wife and 5 children. He joined BrainDen Brain Teaser Forums 6 years ago and his genius was apparent from the very beginning. However, he was not only brilliant but also very respectful which is also why I offered him to be The Moderator here. It was an honor for me that he accepted my offer and that he contributed to this website so much. SP's daughter wrote us that SP enjoyed this BrainDen website and SP wouldn't want to abandon this place without saying Farewell. And that's why let me use this thread to: 1. thank SP for all the great discussions, all the posts where he helped others and all the time he spent here with us 2. share my sincere condolences with SP's family Please join me in this Last Farewell to SP. Thanks.

Alright, I'll add a puzzle to the bunch... You have N computers on a space station. An accident happens, and some of the computers are damaged, but you know the number of good (undamaged) computers is greater than the number of bad (damaged) ones. Your goal is to find *one* computer that's still good. Your only method of testing is the following: Use one computer (say, X) to test another (Y). If X is a good computer, it tells you correctly the status of Y. If X is bad, it may or may not give the correct status of Y; assume it will give whatever answer is least useful to your testing strategy. In worst-case, how many tests must you use to find one computer that's still good? (in terms of N) You're permitted any combination of tests, though keep in mind the bad machines may not be consistent in the results they give you.