Recent research has focused on modeling asset prices by Itô semimartingales. In such a modeling framework, the quadratic variation consists of a continuous and a jump component. This paper is about ...

We prove that Dudley's condition for a.s. convergence of quadratic Brownian variation on a sequence of partitions of $\lbrack 0, 1 \rbrack$ is best possible for the case in which these partitions are ...