### Preservation of unambiguity and inherent ambiguity in context-free languagesPreservation of unambiguity and inherent ambiguity in context-free languages

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 Author Ginsburg, Seymour ♦ Ullian, Joseph Source ACM Digital Library Content type Text Publisher Association for Computing Machinery (ACM) File Format PDF Copyright Year ©1966 Language English
 Subject Domain (in DDC) Computer science, information & general works ♦ Data processing & computer science Abstract Various elementary operations are studied to find whether they preserve on ambiguity and inherent ambiguity of language (“language” means “context-free language”) The following results are established:If $\textit{L}$ is an unambiguous language and $\textit{S}$ is a generalized sequential machine, then (a) $\textit{S}(\textit{L})$ is an unambiguous language if $\textit{S}$ is one-to-one on $\textit{L},$ and (b) $\textit{S}-1(\textit{L})$ is an unambiguous language.Inherent ambiguity is preserved by every generalized sequential machine which is one-to-one on the set of all words.The product (either left or right) of a language and a word preserves both unambiguity and inherent ambiguity.Neither unambiguity nor inherent ambiguity is preserved by any of the following language preserving operations: (a) one state complete sequential machine; (b) product by a two-element set; (c) $\textit{Init}(\textit{L})$ = $[\textit{u}$ ≠ dur in $\textit{L}$ for some $\textit{v}];$ (d) $\textit{Subw}(\textit{L})$ = $[\textit{w}$ ≠ durr in $\textit{L}$ for some $\textit{u},$ $\textit{v}].$ 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 1966-07-01 Publisher Place New York e-ISSN 1557735X Journal Journal of the ACM (JACM) Volume Number 13 Issue Number 3 Page Count 5 Starting Page 364 Ending Page 368

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Source: ACM Digital Library