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We present a new overlay, called the {\em Deterministic Decentralized tree} ($D^2$-tree). The $D^2$-tree compares favourably to other overlays for the following reasons: (a) it provides matching and better complexities, which are deterministic for the supported operations; (b) the management of nodes (peers) and elements are completely decoupled from each other; and (c) an efficient deterministic load-balancing mechanism is presented for the uniform distribution of elements into nodes, while at the same time probabilistic optimal bounds are provided for the congestion of operations at the nodes. The load-balancing scheme of elements into nodes is deterministic and general enough to be applied to other hierarchical tree-based overlays. This load-balancing mechanism is based on an innovative lazy weight-balancing mechanism, which is interesting in its own right.

The issue addressed in this paper focuses on the design and implementation of an advanced information system for Cultural Organizations, which serves as a platform for the exploitation through e-Commerce web services and, in parallel, the protection of copyright and digital rights management of the cultural content. The main components of the information system are: (a) Digital Image Library, which offers specialized services, (b) copyright protection and digital rights management of digitized material and (c) the E-Commerce web services, supported by advanced technologies, for the proper exploitation of the digital cultural content. The work described in this contribution focuses on digitized material of Cultural Heritage and is deployed at several cultural organizations.

We consider the problem of d-dimensional searching (d 3) for four query types: range, partial range, exact match and partial match searching. Let N be the number of points, s be the number of keys specified in a partial match and partial range query and t be the number of points retrieved. We present a data structure with worst case time complexities O(t + logd-2 N), O(t + (d - s) + logs N), O(d + ) and O(t + (d - s) + s ) for each of the aforementioned query types respectively. We also present a second, more concrete solution for exact and partial match queries, which achieves the same query time but has different space requirements. The proposed data structures are considered in the RAM model of computation.