Departmental Papers (CIS)

Date of this Version

7-2011

Document Type

Conference Paper

Comments

From the 38th International Colloquium, ICALP 2011, Zurich, Switzerland, July 4-8, 2011.

Abstract

We introduce nondeterministic streaming string transducers (NSSTs) { a new computational model that can implement MSO-definable relations between strings. An NSST makes a single left-to-right pass on the input string and uses a finite set of string variables to compute the output. In each step, it reads one input symbol, and updates its string variables in parallel with a copyless assignment.We show that the expressive power of NSST coincides with that of nondeterministic MSO-definable transductions. Further, we identify the class of functional NSST; these allow nondeterministic transitions, but for every successful run on a given input generates the same output string. We show that deciding functionality of an arbitrary NSST is decidable with PSPACE complexity, while the equivalence problem for functional NSST is PSPACE-complete. We also show that checking if the set of outputs of an NSST is contained within the set of outputs of a finite number of DSSTs is decidable in PSPACE.

Subject Area

CPS Theory

Publication Source

Lecture Notes in Computer Science: Automata, Languages and Programming

Volume

6756

Start Page

1

Last Page

20

DOI

10.1007/978-3-642-22012-8_1

Copyright/Permission Statement

The original publication is available at www.springerlink.com

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Date Posted: 18 July 2012