English

Stochastic Integrals and Two Filtrations

Probability 2020-09-28 v1

Abstract

In the definition of the stochastic integral, apart from the integrand and the integrator, there is an underlying filtration that plays a role. Thus, it is natural to ask: {\it Does the stochastic integral depend upon the filtration?} In other words, if we have two filtrations, (F)({\mathcal F}_\centerdot) and (G)({\mathcal G}_\centerdot), a process XX that is semimartingale under both the filtrations and a process ff that is predictable for both the filtrations, then are the two stochastic integrals - Y=fdXY=\int f\,dX, with filtration (F)({\mathcal F}_\centerdot) and Z=fdXZ=\int f\,dX, with filtration (G)({\mathcal G}_\centerdot) the same? When ff is left continuous with right limits, then the answer is yes. When one filtration is an enlargement of the other, the two integrals are equal if ff is bounded but this may not be the case when ff is unbounded. We discuss this and give sufficient conditions under which the two integrals are equal.

Keywords

Cite

@article{arxiv.2009.12018,
  title  = {Stochastic Integrals and Two Filtrations},
  author = {Rajeeva L. Karandikar and B. V. Rao},
  journal= {arXiv preprint arXiv:2009.12018},
  year   = {2020}
}
R2 v1 2026-06-23T18:47:03.367Z