Look up: sphere-world

1. Sphere world
   A `sphere world` is a mathematical concept used in robotic motion planning. Essentially, if the environment is represented as a sphere, and the robot and obstacles within the environment are represented as spheres, then it is possible to construct navigation functions which create paths from a start...
   Found on http://en.wikipedia.org/wiki/Sphere_worl
   
   
2. Sphere-world
   The idea of a `sphere-world` was constructed by Henri Poincaré who, while pursuing his argument for conventionalism (see philosophy of space and time), offered a thought experiment about a sphere with strange properties. Poincaré asks us to imagine a sphere of radius R. The temperature ...
   Found on http://en.wikipedia.org/wiki/Sphere-worl