Motivated by a recent conjecture concerning the expressiveness of declarative networking, we propose a formal computation model for "eventually consistent" distributed querying, based on relational transducers. A tight link has been conjectured between coordination-freeness of computations, and monotonicity of the queries expressed by such computations. Indeed, we propose a formal definition of coordination-freeness and confirm that the class of monotone queries is captured by coordination-free transducer networks. Coordination-freeness is a semantic property, but the syntactic class that we define of "oblivious" transducers also captures the same class of monotone queries. Transducer networks that are not coordination-free are much more powerful.
@article{arxiv.1012.2858,
title = {Relational transducers for declarative networking},
author = {Tom Ameloot and Frank Neven and Jan Van den Bussche},
journal= {arXiv preprint arXiv:1012.2858},
year = {2011}
}