fractal
(Hausdorff dimension?)

discretely, it's "change from one scale to another"

esp. useful if trying to make dimension of a fat/discrete set
[eg, price movements]

general principle:
given s'thing defined via limit (deriv),
can also study steps, yielding sequence etc.
[tangent line -> secant line;
 get Lifschitz functions etc.]

can also have lim sup, lim inf
