Conditioned martingales
@article{ECP1955, author = {Nicolas Perkowski and Johannes Ruf}, title = {Conditioned martingales}, journal = {Electron. Commun. Probab.}, fjournal = {Electronic Communications in Probability}, volume = {17}, year = {2012}, keywords = {Doob’s h-transform; change of measure; upward conditioning; downward conditioning; local martingale; diffusion; nullset; Bessel process}, abstract = {It is well known that upward conditioned Brownian motion is a three-dimensional Bessel process, and that a downward conditioned Bessel process is a Brownian motion. We give a simple proof for this result, which generalizes to any continuous local martingale and clarifies the role of finite versus infinite time in this setting. As a consequence, we can describe the law of regular diffusions that are conditioned upward or downward.
}, pages = {no. 48, 1-12}, issn = {1083-589X}, doi = {10.1214/ECP.v17-1955}, url = {http://ecp.ejpecp.org/article/view/1955}}