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Jan 14, 2008

Here's a kind of math question. I'm sure you've heard the problem …

Here's a kind of math question. I'm sure you've heard the problem before.

How can you place 8 queens on a standard chess board so that no queen can attack another queen. This means there is one queen for each row and column and no two queens are in the same diagonal.

I know of one with translational symmetry
I know of one with rotational symmetry
Is it even possible for reflectional symmetry (if so the line of reflection can't be vert, horz or at 45deg)
Can you think of one with no symmetry?

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by unbread

Jan 8, 2008

Oh, I just thought of another problem/interesting thing. My geologist …

Oh, I just thought of another problem/interesting thing.

My geologist friend what over and looking at some publishings on minerals. I asked here what all the triangles with dots in them represented. See said they showed the percentage(placement) of each of 3 minerals for a rock(dot). I'm sure I have the geology part of it wrong but the math part I understood. Each vertex represented a mineral. The closer the dot to the vertex the more the percentage of that mineral, and the closer to the opposite line the less of that mineral (an therefore more of the others). I was curious if the middle (33.3% of each) really was at a height 1/3rd of the altitude. With some simple geometry you can see that it is. I asked if they ever have 4 minerals. She said yes, but then it has to be a pyramid shape. I asked if she meant a tetrahedron, and she said yes (after I made one out of string with my fingers holding the vertices). I was curious then if the center of the polyhedral was really 1/4th the height of the altitude. After even more geometry i found it was. Where I get stuck is when I try to see if it works for a 4-dimensional tetrahedron (is it a hyper tetrahedron?), i.e. the center is 1/5th the altitude.

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by unbread

Jan 8, 2008

Happy Halloween!

Happy Halloween! Photo Sharing and Video Hosting at Photobucket

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by Sweet Cherry Pi

Nov 12, 2007

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Jul 31, 2007

Join our demonstration in Brussels, September 9th. We don't want to …

Join our demonstration in Brussels, September 9th. We don't want to impeach Bush, we want to support the American Public that knows their next president won't be any different. We are uniting all 9/11 truth movements, monetary reformers, Amnesty, Oxfam, Greenpeace, and many more. It is the sick money system - that makes presidents like this, poverty, war, weapon and oil business possible - that needs to change! HELP US NOW!!!

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