# Nonholonomic constraints

1. Jan 11, 2012

### espen180

So far, every nonholonomic constraint I have seen can be expressed as a collection of inequalities involving the coordinates of the system. For example, a small ball rolling down a sphere with radius a has the constraint $r^2-a^2\geq 0$, where r is the radial coordinate of the ball.

Can every nonholonomic constraint be written in this form? If not, I would appreciate a counterexample.