A Spatial Logic for Querying Graphs

Lu a Cardelli, Philippa Gardner and Giorgio Ghelli1 Abstra t. We study a spatial logi for reasoning about labelled dire ted graphs, and the appli ation of this logi to provide a query language for analysing and manipulating su h graphs. We give a graph des ription using onstru ts from pro ess algebra. We introdu e a spatial logi in order to reason lo ally about disjoint subgraphs. We extend our logi to provide a query language whi h preserves the multiset semanti s of our graph model. Our approa h ontrasts with the more traditional set-based semanti s found in query languages su h as TQL, Strudel and GraphLog. 1 Introdu tion Semi-stru tured data plays an important role in the ex hange of information between globally distributed appli ations: examples in lude BibTex les and XML do uments. Whilst the resear h ommunity mostly agree on de ning semistru tured data using labelled dire ted graphs or trees with `graphi al' links, the study of how to query, modify and manipulate su h data is still very a tive. Motivating Examples A standard example used by the semi-stru tured data ommunity [ABS00℄ is a bibtex le with an arti le entry of the form: x y citation