Similar to this question, but for a very different situation.
I've been working-up some example code to accompany a proposed programming challenge and asking questions about the difficult bits. In my latest question, the answer I've received suggests that I use an Octree instead of a BSP-Tree.
But Wikipedia says it's patented. And a public programming challenge -- much more than a private program or even free (beer) software -- really is encouraging people to reuse the idea without regard to ownership.
So I can't (legally or in good conscience) use it here, can I?
More generally, What do I need to find out (or do) when I learn that an algorithm I want to use is "Patented"?