Conditioning to avoid zero via a class of concave functions for one-dimensional diffusions

Kosuke Yamato

Published 2024-08-26Version 1

For one-dimensional diffusions on the half-line, we study a specific type of conditioning to avoid zero. We introduce martingales via a class of functions that are concave with respect to the scale function and similar to the densities of quasi-stationary distributions. The conditioning is formulated through the exit times of the martingale, and its existence is shown. We investigate its relation to the Yaglom limit and the absolute continuity relations of the limit processes at time infinity.