PSearch is based on Paramsearch, a tool created by Antal van den Bosch for automatic algorithmic parameter optimisation for TiMBL and other machine learning algorithms. Paramsearch is available for download from http://ilk.uvt.nl/software/. PSearch works basically on the same principles as Paramsearch, with the major difference being the way that the sizes of the progressive training and evaluation data sets are generated. Another difference is that PSearch can utilise all of the TiMBL algorithms.