Abstract. Relational algebra has been a crucial foundation for relational database systems, and has played a large role in enabling their success. A corresponding XML algebra for XML query processing has been more elusive, due to the comparative complexity of XML, and its history. We argue that having a sound algebraic basis remains important nonetheless. In this paper, we show how the complexity of XML can be modeled effectively in a simple algebra, and how the conceptual clarity attained thereby can lead to significant benefits.
Stelios Paparizos, H. V. Jagadish