Velocity is defined as:

where **x** is the displacement and *t* = ‖**t**‖ is the independent time interval, the distime of a parallel reference motion. The inverse of **v** is the function defined by the reciprocal of this derivative:

The converse of **v** is **w**, the lenticity, which is defined as:

where **t** is the dischronment and *s* = ‖**s**‖ is the independent distance, the distance of a parallel reference motion. The inverse of **v** is the function defined by the reciprocal of this derivative:

If **s** were always the dependent variable and **t** were always the independent variable, then **v** and **w** would be inverses of each other. But that is not the case here. The dependency of **s** and **t** changes between **v** and **w**.

Since **x** and **z** are symmetric, so are **v** and **w**. Interchange **x** and **z** and then *s* and *t* to get the corresponding equation for **v** and **w**, or other pairs of symmetric variables such as **a** and **b**, the acceleration and the relentation.