A declarative coordination language

We describe Gammalog, a logic language whose semantics is based on the chem ical metaphor. The language combines the ability of describing coordination by transformation rules on a shared-dataspace, as in Gamma, with the execu tion model of logic programming. The main feature of Gammalog is that the d eclarative reading of programs is not restricted to the pure logic language but it also includes the coordination mechanisms. This feature makes Gamma log a promising alternative to other coordination models which can be embed ded in logic programming. We present the language syntax, its formal semant ics, and a prototype implementation based on Godel, which inherits its stro ngly typed framework. As an example of the expressive power of the language we provide the specification of a simple operating system. (C) 2001 Elsevi er Science Ltd. All rights reserved.