Please use this identifier to cite or link to this item: http://hdl.handle.net/1813/7279
 Title: On the Complexity of Reasoning in Kleene Algebra Authors: Kozen, Dexter Keywords: computer sciencetechnical report Issue Date: Mar-1997 Publisher: Cornell University Citation: http://techreports.library.cornell.edu:8081/Dienst/UI/1.0/Display/cul.cs/TR97-1624 Abstract: We study the complexity of reasoning in Kleene algebra and *-continuous Kleene algebra in the presence of extra equational assumptions $E$; that is, the complexity of deciding the validity of universal Horn formulas $E\imp s=t$, where $E$ is a finite set of equations. We obtain various levels of complexity based on the form of the assumptions $E$. Our main results are: for *-continuous Kleene algebra, \begin{itemize} \item if $E$ contains only commutativity assumptions $pq=qp$, the problem is $\Pi_1^0$-complete; \item if $E$ contains only monoid equations, the problem is $\Pi_2^0$-complete; \item for arbitrary equations $E$, the problem is $\Pi_1^1$-complete. \end{itemize} The last problem is the universal Horn theory of the *-continuous Kleene algebras. This resolves an open question of Kozen (1994). URI: http://hdl.handle.net/1813/7279 Appears in Collections: Computer Science Technical Reports

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