The Department of Archaeological Science of the University of Pisa is undertaking the MAPPA project, which is a research project in which archaeologists, geologists, mathematicians will study predictive modelling tools applied to the archaeological potential of an urban area. The project main objectives are:

- Enhancing the development in archaeological research by fostering collaboration among different sectors and by developing a common langua­ge.

- Creating a model that may be applied to all urban centres in order to facilitate land use decisions. Within this con­text, we propose predictive mathe­matical models, which will have an impact on archaeological he­ritage protection, territorial planning and historical knowledge.

- Making raw data from archaeological in­vestigations available. The project proposes that after acknowledging au­thorship of the data, the latter shall be made publicly available and easy to consult.

Based on the discussions between the mathematical, archaeological and geological teams, an analogy arose between the criteria used for attri­buting archaeological potential and those used for assigning importance to web pages by search en­gines. Indeed, the key issue of the archaeological interpretation process, from an abstract viewpoint, is the identification of the relations that exist among finds, both in spatial terms and in functional terms. In other words, the presen­ce of a particular find near another that has already been discovered could strengthen or weaken the pro­bability that they will form a more complex structu­re, and so strengthen or weaken the archaeological potential of the area itself. This is exactly the crite­ria upon which page ranking algorithms are based, whereby each web page attributes importance to the web pages it points to (via a link) and, in turn, recei­ves importance from the web pages it receives a link from. In order to adapt a page rank model to the determi­nation of archaeological potential, variants need to be created:

- A three-dimensional grid will model the subsurface of the urban area. A single cell plays the role of a web page, and its importance will be the archaeological potential;

- The information available for a cell will be used: in a relative manner, to build the elements of the matrix that, like in page rank models, assigns the transfer of importance among cells; in an abso­lute manner, providing the absolute value of the archaeological potential;

- The matrix controlling the transfer of importance will be constructed on the basis of categories used for classifying the archaeological finds. The categories will characterise the geometry of the distribution of importance;

- Geological information will be used in a binary manner, allowing to exclude certain cells from the calculation of archaeological potential.

Finally, the MAPPA project will realise an Archaeological Information System able to define the specific nature of archaeological practice, and to manage the heterogeneous data which describe the urban archaeological complexity.