previous similar studies that showed a reduction of 40% of the error rate on the main syntactic relations with a French corpus. The remaining errors are due to four different phenomena. First, the normalization step, prior to parsing, needs to be enhanced. Concerning LP, there are still lexicon gaps, wrong class assignments and a still unsatisfactory handling of numerical expressions. In addition, and like (Sutcliffe et *al.,* 1995), we identified a weakness of LP regarding coordination. A specific study of the coordination system in LP and in the biological texts may be necessary. Finally, some ambiguous nominal and prepositional attachments still remain in spite of term simplification. These may be resolved in a post-processing step like in ExtrAns that uses a corpus based approach to retrieve the correct attachment from the different linkages given by LP for a sentence. Thus, the parser adaptation relies on three methods: the exploitation of a small base of morphological rules, the modification of the grammar, and an adequate integration that relieve the parser from all what do not directly deal with structural ambiguity (POS and term tagging, especially).

## 7. Conclusion

We have presented in this paper a platform that has been designed to enrich specialized domain documents with linguistic annotations. While developments and experiments have been performed on biomedical texts, we assume that this architecture is generic enough to process other specialized documents. The platform is designed as a framework using existing NLP tools which can be substituted by others if necessary. Several NLP modules have been integrated: named entity tagging, word and sentence segmentation, POS tagging, lemmatization, term tagging, and syntactic parsing. Semantic type tagging and anaphora resolution are currently being under stress. We also focused on the system performance, since this point is crucial for most Internet applications. We have experimented a distributed design of the platform, by splitting the corpus in equal parts: this strategy dramatically increased the overall performance (see (Ravichandran et al., 2004). We have also shown that Ogmios is a robust NLP platform with respect to the high heterogeneity of the document sizes and types. These first experiments show that a deep analysis of web documents is possible. Besides the necessary improvement the Ogmios platform, our next goal is to assess the impact of NLP on IR performance. Our hypothesis is that this impact should be higher in the case of a specialized search engines than for a generic IR framework, on which the IR-NLP cooperation has mainly been tested until now. Specific experiments are currently carried out in the ALVIS project to test the potential resulting enhanced functionalities on a microbiological search engine.

## Acknowledgements

This work is supported by the EU 6th Framework Program in the IST Priority under the ALVIS project. The material benefits from interactions with the ALVIS partners, especially with INRA-MIG.

## References

Alphonse, E., Aubin, S., Bessieres, P., Bisson, G., Hamon, T., Laguarrigue, S., Manine, A.P., Nazarenko, A., Nedellec, C., Vetah, M.O.A., Poibeau, T., Weissenbacher, D.: Event-based 