Mappings in most federated databases are conceptualized and implemented as black-box transformations between source schemas and a federated schema. This approach does not allow specific mappings to be declared once and reused in other situations. We present an alternative approach, in which...

With the emerging trend ofWeb 3.0 and the resulting huge amount of usergenerated semantically-enriched data, improved ways of knowledge visualization and human computer interaction are needed. We present several techniques of visualizing particularly spatial knowledge in largely scalable, clear...

A system that implements the byzantine agreement algorithm is supposed to be very reliable and robust because of its fault tolerating feature. For very realistic environments, byzantine agreement protocols becomes inadequate, because they are based on the assumption that failures are controlled...