Task: Text Simplification
Input (English): more formally , vorticity can be related to the amount of " circulation " or " rotation " -lrb- or more strictly , the local angular rate of rotation -rrb- in a fluid.
Output (English): more formally , vorticity can be related to the amount of " circulation " or " rotation " -lrb- or the local angular rate of rotation -rrb- in a fluid.