Parallel RAMs with owned global memory and deterministic context-free language recognition

We identify and study a natural and frequently occurring subclass of Concurrent Read, Exclusive Write Parallel Random Access Machines (CREW-PRAMs). Called Concurrent Read, Owner Write, or CROW-PRAMs, these are machines in which each global memory location is assigned a unique "owner" processor, which is the only processor allowed to write into it. Considering the difficulties that would be involved in physically realizing a full CREW-PRAM model, it is interesting to observe that in fact, most known CREW-PRAM algorithms satisfy the CROW restriction or can be easily modified to do so. This paper makes three main contributions. First, we formally define the CROW-PRAM model and demonstrate its stability under several definitional changes. Second, we precisely characterize the power of the CROW-PRAM by showing that the class of languages recognizable by it in time O(log n) (and implicitly with a polynomial number of processors) is exactly the class LOGDCFL of languages log space r...

• Type: Journal
• Year: 2000
• Where: JACM
• Authors: Patrick W. Dymond, Walter L. Ruzzo
• Keywords: Context-free Languages, JACM 2000, Parallel Random Access, Random Access