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Star height problem - Definition and Overview |
| Related Words: Aggravation, Annoyance, Anxiety, Basis, Bore, Bug, Bugbear, Burden, Case, Catch, Catechism |
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The star-height problem in formal language theory is the question whether all regular languages can be expressed using regular expressions with a limited nesting depth of Kleene stars. Specifically, is a nesting depth of more than 2 required? If so, can we determine how many are required?
This theoretical problem remained open for 25 years until it was solved by Kosaburo Hashiguchi. The answer to all questions is yes: Hashiguchi published an algorithm to determine an expression's star height in 1988.
Also see generalized star height problem.
References
- Kosaburo Hashiguchi, Regular languages of star height one, Information and Control, 53: 199-210, 1982
- Kosaburo Hashiguchi, Algorithms for Determining Relative Star Height and Star Height, Inf. Comput. 78(2): 124-169, 1988
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Example Usage of problem |
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papadimitriou: @stevenagata love flavors.me! Haven't had time to do my page yet. Only problem: flash so no iPhone... |
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stefangelfgren: "One problem with speaking the cultural language to the world but not to the church is that the product cannot match the advertisment." |
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techgle_hosting: Hosting-Hosting: HELP. Godaddy hosting. domain admin problem http://forum.techgle.com/showthread.php?t=275483 |
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