TY - GEN
T1 - On read-once vs. multiple access to randomness in logspace
AU - Nisan, Noam
PY - 1990
Y1 - 1990
N2 - In the correct definition of randomized space-bounded computation, the machine has access to a random coin. The coin can be flipped at will, but outcomes of previous coin flips cannot be recalled unless they are saved in the machine's limited memory. In contrast to this read-once mechanism of accessing the random source, one may consider Turing machines which have access to a random tape. Here, the random bits may be multiply accessed by the machine. The author demonstrates a very concrete sense in which multiple access to the random bits is better than read-once access to them: Every language accepted with bounded two-sided error by a read-once-randomized logspace machine can be accepted with zero error by a randomized logspace machine having multiple access to the random bits.
AB - In the correct definition of randomized space-bounded computation, the machine has access to a random coin. The coin can be flipped at will, but outcomes of previous coin flips cannot be recalled unless they are saved in the machine's limited memory. In contrast to this read-once mechanism of accessing the random source, one may consider Turing machines which have access to a random tape. Here, the random bits may be multiply accessed by the machine. The author demonstrates a very concrete sense in which multiple access to the random bits is better than read-once access to them: Every language accepted with bounded two-sided error by a read-once-randomized logspace machine can be accepted with zero error by a randomized logspace machine having multiple access to the random bits.
UR - http://www.scopus.com/inward/record.url?scp=0025661863&partnerID=8YFLogxK
M3 - Conference contribution
AN - SCOPUS:0025661863
SN - 0818620722
T3 - Proc Fifth Annu Struct Complexity Theor
SP - 179
EP - 184
BT - Proc Fifth Annu Struct Complexity Theor
PB - Publ by IEEE
T2 - Proceedings of the Fifth Annual Structure in Complexity Theory Conference
Y2 - 8 July 1990 through 11 July 1990
ER -