Abstract
Let M be a continuous two-parameter L4-martingale, vanishing on the axes, and f a C-function. In Itô's formula for f(M2) a new martingale M̃ is involved. This martingale can be interpreted formally as the stochastic integral ∫∂1M∂2M and it coincides with the martingale JM introduced by Cairoli and Walsh when M is strong. In this paper we prove that if M has path-independent variation, then M and M̃ are orthogonal. Also. we give some counter-examples to the reciprocal implication. © 1987.
Original language | English |
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Pages (from-to) | 31-49 |
Journal | Stochastic Processes and their Applications |
Volume | 24 |
DOIs | |
Publication status | Published - 1 Jan 1987 |
Keywords
- path-independent variation
- quadratic variation
- two-parameter martingales