Representing knowledge in archaeology: from cataloguing cards to Semantic Web

Knowledge has been the driving force behind the Italian National Catalogue of Cultural Heritage. In the first stage, when the catalogue was mainly based on hand written paper cards describing objects regardless of their complexity, and intended for manual access by humans, the expert’s tacit knowledge remained unexpressed, and the card had a simple structure. Computer based applications initially relied on the features of Information Retrieval Systems, and simply converted typewritten cards into electronic documents. As results were quite disappointing, it became evident that a more formal representation of information was needed. The Italian experience led to the definition of a model for objects (simple, complex, aggregation of objects) with quite a large number of fields. Even if the schema was often perceived as too rigid, it proved to be effective for data exchange, and long lasting (the present XML model is almost the same, just with a different syntax). However, its main drawback was the "object centred" approach, and the impossibility of representing significant semantic associations with other disciplines. In this sense, a major objective, the contextualization of objects, remained unattained. The web has been a "cultural revolution", because information is available everywhere, and users feel the need to combine different sources of knowledge. This semantic interoperability issue is often dealt with by adopting a metadata based approach (Dublin Core is the most popular). However, the metadata approach has the intrinsic limit that metadata are properties we "predicate" about items they refer to, and it is difficult, if not impossible, to derive new knowledge from the old. The Semantic Web perspective is much more ambitious, as the aim is to represent, export and share knowledge in a "machine understandable" way, and to allow intelligent agents to reason about it. In this light, scholars’ knowledge must be formalized and made explicit as ontology, and very probably we will have to agree on a different model to represent objects, in a distributed and multicultural environment. This is not the end of the traditional scholars’ knowledge, but a more effective environment for making this knowledge available to all users.