Control function for rough paths
= Control function for rough paths
{title2=$\omega(s,u)+\omega(u,t)\leq\omega(s,t)$}
A control is a continuous nonnegative function on ordered pairs of times, zero on the diagonal and superadditive as displayed. It measures the size of increments of a <rough path>, typically through $|X^{(k)}_{s,t}|\leq\omega(s,t)^{k/p}$. Continuous finite variation gives suitable controls, which let local estimates be stated without tying them to a particular time parametrization.