Technical Report Number
Consensus, which requires processes with different input values to eventually agree on one of these values, is a fundamental problem in fault-tolerant computing. We study this problem in the context of asynchronous shared-memory systems. In our model, shared-memory consists of a sequence of cells and supports a specific set of operations. Prior research on consensus focussed on its solvability in shared-memories supporting specific operations. In this paper, we investigate the following general question: Let OP1 and OP2 be any two sets of operations such that each set includes read and write operations. Suppose there is no consensus protocol for N processes in a shared-memory that supports only operations in OP1 and in a shared-memory that supports only operations in OP2. Does it follow that there is no consensus protocol for N processes in a shared-memory that supports all operations in OP1 and all operations in OP_2? This question is in the same spirit as the robustness question, but there are significant differences, both conceptually and in the models of shared-memory for which the two questions are studied. For deterministic types, the robustness question has been known to have a positive answer, In contrast, we prove that the answer to the question posed above is negative even if operations are deterministic.
Dartmouth Digital Commons Citation
Jayanti, Prasad, "Compositional Reasoning is not possible in Determining the Solvability of Consensus" (1996). Computer Science Technical Report PCS-TR96-277. https://digitalcommons.dartmouth.edu/cs_tr/128