Result: Translational lemmas for DLOGTIME-uniform circuits, alternating TMs, and PRAMs
Sharp Corporation, Osaka 545-8522, Japan
Mitsubishi Electric Corporation, Tokyo 100-8310, Japan
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Mathematics
Further Information
We present translational lemmas for the three standard models of parallel computation, and apply them to obtain tight hierarchy results. It is shown that, for arbitrarily small rational constant e > 0, (i) there is a language which can be accepted by a UE-uniform circuit family of depth c(1 + ∈)(log n)r1 and size dnr2(1+∈) but not by any UE-uniform circuit family of depth c(log n)r1 and size dnr2, (ii) there is a language which can be accepted by a c(9 + ∈) (log n)r1 -time d(4 + ∈) log n-space ATM with l worktapes but not by any c(log n)r1 -time d log n-space ATM with the same I worktapes if the number of tape symbols is fixed, and (iii) there is a language which can be accepted by a c(1 + ∈)(log n)r1 -time PRAM with dnr2(1+∈) processors but not by any c(log n)r1 -time PRAM with dnr2 processors. Here, c > 0, d ≥ 1, r1 > 1, and r2 ≥ 1 are arbitrary rational constants, and l ≥ 2 is an arbitrary integer.