Some Experimental Results in Implementing a Logic Language with Multi-head Clauses on a Transputer Architecture

We focus on the distributed implementation of an extended logic language (called ROSE) based on multi-head clauses which can be useful to implement parallel logic objects where state change is performed by unification and recursion. Distinguishing features of ROSE are OR-parallelism with committed-choice behaviour and the AND-parallel execution of subgoals which do not share variables. We present the real implementation of ROSE on a Transputer-based architecture, and discuss some experimental results obtained by considering different allocation policies for processes. These allocation policies correspond to forms of inter- and intra-object parallelism when objects with state are implemented as ROSE programs. Obtained figures help in understanding which is the optimal allocation policy to adopt on the basis of an estimation of the time necessary for performing the distributed unification and the guard and body evaluation.