I agree with Erick that you probably need to give your client a list of concrete examples, and perhaps to explain the trade-offs.
All stemmers both overstem and understem. Understemming means that some forms of a word won’t get searched. For example, without stemming, searching for “dogs” would not retrieve documents containing the word “dog”. Generally there is a precision/recall tradeoff where reducing understemming increases overstemming. The problem with aggressive stemmers like the Porter stemmer, is that they overstem. The original Porter stemmer for example would stem “organization” and “ organic” both to “organ” and “generalization” , “generous”and “generic” to “ gener” * For background on the Porter stemmers and lots of examples see these pages: http*://snowball.tartarus.org/algorithms/porter/stemmer.html<http://snowball.tartarus.org/algorithms/porter/stemmer.html> * *http://snowball.tartarus.org/algorithms/english/stemmer.html*<http://snowball.tartarus.org/algorithms/english/stemmer.html> This paper on the Kstem stemmer lists cases where the Porter stemmer understems or overstems and explains the logic of Kstem: "Viewing Morphology as an Inference Process" (*Krovetz*, R., Proceedings of the Sixteenth Annual International ACM SIGIR Conference on Research and Development in Information Retrieval, 191-203, 1993). *http://ciir.cs.umass.edu/pubfiles/ir-35.pdf*<http://ciir.cs.umass.edu/pubfiles/ir-35.pdf> " Tom http://www.hathitrust.org/blogs/large-scale-search
