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With the increasingly huge amount of data located in various databases and the need for users to access them, distributed information retrieval (DIR) has been at the core of the preoccupations of a number of researchers. Indeed, numerous DIR systems and architectures have been proposed including the broker-based architecture. Moreover, providing DIR with more flexibility and adaptability has led researchers thinking to build DIR with software agents. Thus, this research proposes a design and an implementation of a novel system based on the broker-based architecture and the peer-to-peer (P2P) network called broker-based P2P network. The proposed architecture is implemented with a multi-agent system (MAS) where the main agent playing the role of the broker, receives query from a peer agent and forwards them to other peer agents each with their index and resources. Upon completing retrieval process at each peer agent, results are directly sent to the peer agent that initiated the query without using the broker agent. Java Agent DEvelopment framework (JADE) is used to implement the agents and, for experiments, TERRIER (TERabyte RetRIEveR) is extended and used as the search engine to retrieve the Text Retrieval Conference (TREC) collections dataset notably TREC-6. The peer agent that originated the query progressively collects results coming from other peer agents, normalises and merges them and then proceeds with re-ranking. For normalisation, MinMax and Sum that are unsupervised normalisation methods are used.

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Procedural content generation (PCG) methods are commonly employed in computer games, simulations, and other related industries. While these methods are used for levels, terrains, stories and missions, their usage for procedural city generation is relatively rare because cities are heterogeneous structures with different components such as roads, layouts and buildings that depend on and affect each other. Additionally, ancient cities grew organically to areas that are safe and to those that provide food and water. This resulted in cities that do not have apparent regular patterns, such as rectangular building blocks. We propose an approach that uses cellular automata (CA) that generates clusters of areas. The CA is repeated for each cluster to hierarchically create different levels of the city. This procedure creates an organic city layout with fractal properties. The layout specifies the building blocks, main roads, and foliage. We also present a set of methods that can transform this layout into a three-dimensional model of the city. The results are promising; cities can be created in under a minute with minimal required input, and the resulting virtual city looks organic, rather than an algorithmic layout that has repeating patterns.

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