Recall word- Base um0.510210.890.40 Synset- Based UM Table 1: Com parison between word-based UM and sy nset-based UM m antic coherence, which is not guaranteed in case of crim ination. In al*iA97: Advances in Artificial a word-based ret reva Intelligence. Springer verlag As for recall, it also gains some points(15%),even C. Peters. andn calzolari if it rem ains quite low. However. this does not seen 1998. Applying eurowordnet to cross-lang a serious draw back for a pure recom mender system text retrieval. Computers and Humanities, 32 where there is no t he need to answer an explicit 3):185-207 Neil w. van duke and Adrian S retrieval systems), but rather the need is for an high Vivacqua. 1999. Let's browse: A collaborat ive quality (i.e. the precision) of the propo sals web browsing ager Proceedings of the 1999 International Confer 5 Con c lu sion terfaces, Collaborative Filtering and Collabora- w versIo of siteif. a re ive Interfaces, pages 65-68 om mender system for a Web site of multilingual B. Magnini and G. Cavaglia. 2000. Integrating news. Exploiting a content-based document repre subject field codes into WordNet. In proceedings sentation. we have described a model of the user's of lrec-2000. Second international conference ts based on word rather that on sim ply on Language Resources and Evaluation, Athe ds. The main ad of this approach that semantic accuracy increases and that the model B Magnini and C. Strapparava. 2000. Experiments is independent n word dom ain disam big tion for pa rallel texts To give a quantitative estim ation of the im prove In Proc. of SIGLEX Workshop on Word Senses ments induced by a content-based approach, a com and Multi-linguality, Hong- Kong, October. held parative experiment sense-based vs. word-based In conJunction with A CL 2000 user model- has been carried out, which has showed G. Miller. 1990. An on-line lexical database. Inter a significant higher precision in the system recom national Journal of Lexicogr aphy, 1 3(4): 235-312 M. Minio and C. Tasso. 1996. User modeling for in here are several areas for future development s form ation filtering on internet services: Exploiting One point is to im prove the disam biguation algo an extended version of the umt shell. In Proc rithms w hich are at the basis of the dot of Workshop on User Modeling for Information resentation. A prom ising direction (proposed in Filtering on the World Wide Web, Kailia-Kuna and Strapparava, 2000)) is to design spe Haw aii, January. held in conjunction with UM 96 ific algorithms which consider the synset intersec- A. Stefani and C. Strapparava. 1998.Personaliziong tion of parallel news access to web sites: The siteif pro ject. In Proc. of A second working direction concerns the possi b second Workshop on Adaptive Hypertext and Hy ity to develop clustering algorithms over the senses permedia, Pittsburgh, June. held in conjunction of the sem antic net work. For exam ple, once the user with hyPerteXt 98 odel net work is built, it could be useful to dynam- C. Strapparava, B. Magnini, and A. Stefani. 2000 ically infer some homogeneous user interest areas. Sense-based user modelling for web sites. In Adap This would allow to arrange in unifo rm dynam ic tive Hypermedi a and Adaptive Web- Based ys- groups the recom mended docum s tems- Lecture Notes in Computer Science 1892 ces R. Armstre D. Freia T. Joachim d T Mitchell. 1995. Webwatcher: A learning ap rld wide web AAAI Spring Symposium g from Heterogeneous and Distributed Environ ments. Stanford. March WordNet for italian and its use for lexical dNews Categories Precision Recal l Precision Recal l Word-Based UM 0.51 0.21 0.89 0.40 Synset-Based UM 0.85 0.36 0.97 0.43 Table 1: Comparison between word-based UM and synset-based UM mantic coherence, which is not guaranteed in case of a word-based retrieval. As for recall, it also gains some points (15%), even if it remains quite low. However, this does not seem a serious drawback for a pure recommender system, where there is no the need to answer an explicit query (as it happens, for instance, in information retrieval systems), but rather the need is for an high quality (i.e. the precision) of the proposals. 5 Conclusions We have presented a new version of SiteIF, a rec￾ommender system for a Web site of multilingual news. Exploiting a content-based document repre￾sentation, we have described a model of the user's interests based on word senses rather that on simply words. The main advantages of this approach are that semantic accuracy increases and that the model is independent from the language of the news. To give a quantitative estimation of the improve- ments induced by a content-based approach, a com￾parative experiment - sense-based vs. word-based user model - has been carried out, which has showed a signicant higher precision in the system recom￾mendations. There are several areas for future developments. One point is to improve the disambiguation algo￾rithms which are at the basis of the document rep￾resentation. A promising direction (proposed in (Magnini and Strapparava, 2000)) is to design spe￾cic algorithms which consider the synset intersec￾tion of parallel news. A second working direction concerns the possibil￾ity to develop clustering algorithms over the senses of the semantic network. For example, once the user model network is built, it could be useful to dynam￾ically infer some homogeneous user interest areas. This would allow to arrange in uniform dynamic groups the recommended documents. References R. Armstrong, D. Freitag, T. Joachim, and T. Mitchell. 1995. Webwatcher: A learning ap￾prentice for the world wide web. In Proc. of AAAI Spring Symposium on Information Gather￾ing from Heterogeneous and Distributed Environ- ments, Stanford, March. A. Artale, B. Magnini, and C. Strapparava. 1997. WordNet for italian and its use for lexical dis￾crimination. In AI*IA97: Advances in Articial Intel ligence. Springer Verlag. J. Gonzalo, F. Verdejio, C. Peters, and N. Calzolari. 1998. Applying eurowordnet to cross-language text retrieval. Computers and Humanities, 32(2- 3):185{207. Henry Lieberman, Neil W. Van Dyke, and Adrian S. Vivacqua. 1999. Let's browse: A collaborative web browsing agent. In Proceedings of the 1999 International Conference on Intel ligent User In￾terfaces, Collaborative Filtering and Collabora￾tive Interfaces, pages 65{68. B. Magnini and G. Cavaglia. 2000. Integrating subject eld codes into WordNet. In Proceedings of LREC-2000, Second International Conference on Language Resources and Evaluation, Athens, Greece, June. B. Magnini and C. Strapparava. 2000. Experiments in word domain disambiguation for parallel texts. In Proc. of SIGLEX Workshop on Word Senses and Multi-linguality, Hong-Kong, October. held in conjunction with ACL2000. G. Miller. 1990. An on-line lexical database. Inter￾national Journal of Lexicography, 13(4):235{312. M. Minio and C. Tasso. 1996. User modeling for in￾formation ltering on internet services: Exploiting an extended version of the UMT shell. In Proc. of Workshop on User Modeling for Information Filtering on the World Wide Web, Kailia-Kuna Hawaii, January. held in conjunction with UM'96. A. Stefani and C. Strapparava. 1998. Personaliziong access to web sites: The siteif project. In Proc. of second Workshop on Adaptive Hypertext and Hy￾permedia, Pittsburgh, June. held in conjunction with HYPERTEXT 98. C. Strapparava, B. Magnini, and A. Stefani. 2000. Sense-based user modelling for web sites. In Adap￾tive Hypermedia and Adaptive Web-Based Sys￾tems - Lecture Notes in Computer Science 1892. Springer Verlag