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Author Hopcroft, J. E. ♦ Ullman, J. D.
Source ACM Digital Library
Content type Text
Publisher Association for Computing Machinery (ACM)
File Format PDF
Copyright Year ©1969
Language English
Subject Domain (in DDC) Computer science, information & general works ♦ Data processing & computer science
Abstract Classes of tape-bounded Turing machines similar to the on-line and off-line Turing machines, but without the restrictions that each machine halt and be deterministic, are studied. It is shown that the lower bounds on tape complexity of [1] depend on neither the halting assumption nor determinism. The existence of a dense hierarchy of complexity classes likewise does not depend on the halting assumption, and it is shown that below log $\textit{n}$ tape complexity there exists a dense hierarchy of complexity classes for two-way nondeterministic devices. It is also shown that the complexity classes of one-way, nondeterministic machines below linear large complexity are not closed under complementation and are larger that the corresponding deterministic complexity class.
ISSN 00045411
Age Range 18 to 22 years ♦ above 22 year
Educational Use Research
Education Level UG and PG
Learning Resource Type Article
Publisher Date 1969-01-01
Publisher Place New York
e-ISSN 1557735X
Journal Journal of the ACM (JACM)
Volume Number 16
Issue Number 1
Page Count 10
Starting Page 168
Ending Page 177


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Source: ACM Digital Library