Abstract: A computer system has a plurality of processors, each having a local memory. An expression is represented by operands and operations and is expressed in a form of a tree. The operands are assigned to leaf nodes of the tree and the operations are assigned to interior nodes. Processors which store an operand represented by a leaf node are assigned to the leaf node. The tree is traced in a bottom-up fashion to determine a set of candidate processors to be assigned to each of the interior nodes. The candidate processors are determined from processors which are assigned to children nodes of each interior node in accordance with a majority method. The majority method is based on a rule that a processor which is most frequently assigned to the children nodes of an interior node is determined as a candidate processor. A root processor is assigned to a root node of the interior nodes from the candidate processors.