Abstract. This paper presents Synapse, a scalable protocol for information retrieval over the inter-connection of heterogeneous overlay networks. Applications on top of Synapse see those intra-overlay networks as a unique inter-overlay network. Scalability in Synapse is achieved via co-located nodes, i.e. nodes that are part of multiple overlay networks at the same time. Co-located nodes, playing the role of neural synapses and connected to several overlay networks, allow a larger search area and provide alternative routing. Synapse can either work with "open" overlays adapting their protocol to synapse interconnection requirements, or with "closed" overlays that will not accept any change to their protocol. Results from simulation and experiments show that Synapse is scalable, with a communication and state overhead scaling similarly as the networks interconnected. Thanks to alternate routing paths, Synapse also gives a practical solution to network partitions. We precisely capture the behavior of traditional metrics of overlay networks within Synapse and present results from simulations as well as some actual experiments of a client prototype on the Grid'5000 platform. The prototype developed implements the Synapse protocol in the particular case of the interconnection of many Chord overlay networks.

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In this paper we provide a strongly complete axiomatization of a temporal epistemic logic in which non-rigid sets of agents are allowed. Using this framework, we prove a number of properties of the blockchain protocol with respect to the given set of axioms and premises.

The paper identifies necessary steps to create a national information system for management and preservation of cultural heritage documentation. The Republic of Serbia, where the digitization of cultural heritage is recognized as a segment of cultural development and officially accepted as one of the methods for preservation and presentation of heritage documentation, is taken as a case study. The paper describes the evolutionary path of the digitization process in Serbia and analyzes the importance of the adoption of a legal framework and establishment of national standards in the process of achieving the uniqueness in cultural heritage long-term sustainable documentation management and preservation across cultural institutions.

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