We have a 3 dimensional space.
At all points of this space a value(density for example) is defined.
This value changes smoothly.
The question is: "Can I always cut a cylinder from this space, so that it's center of mass is on it's main axis?"
By "smoothly" there are 2 cases to consider:
- along any curve, the value "do not jump"
- first condition holds, moreover the derivative of the value "do not jump" too.