@article{ECP1035,
author = {Jan Swart},
title = {A 2-Dimensional SDE Whose Solutions are Not Unique},
journal = {Electron. Commun. Probab.},
fjournal = {Electronic Communications in Probability},
volume = {6},
year = {2001},
keywords = {Stochastic differential equation, pathwise uniqueness / strong uniqueness, diffusion process.},
abstract = {In 1971, Yamada and Watanabe showed that pathwise uniqueness holds for the SDE $dX= \sigma (X)dB$ when sigma takes values in the n-by-m matrices and satisfies $|\sigma (x)- \sigma (y)| < |x-y|\log(1/|x-y|)^{1/2}$. When $n=m=2$ and $\sigma$ is of the form $\sigma _{ij}(x)= \delta_{ij}s(x)$, they showed that this condition can be relaxed to $| \sigma(x)-\sigma(y)| < |x-y|\log(1/|x-y|)$, leaving open the question whether this is true for general $ 2\times m$ matrices. We construct a $2\times 1$ matrix-valued function which negatively answers this question. The construction demonstrates an unexpected effect, namely, that fluctuations in the radial direction may stabilize a particle in the origin.},
pages = {no. 6, 67-71},
issn = {1083-589X},
doi = {10.1214/ECP.v6-1035},
url = {http://ecp.ejpecp.org/article/view/1035}}