### Abstract

In this paper we study the problem of deciding whether a given compressed string contains a square. A string x is called a square if x = zz and z = u ^{k} implies k = 1 and u = z. A string w is said to be square-free if no substrings of w are squares. Many efficient algorithms to test if a given string is square-free, have been developed so far. However, very little is known for testing square-freeness of a given compressed string. In this paper, we give an O(max(n ^{2}, n log ^{2} N))-time O(n ^{2})-space solution to test square-freeness of a given compressed string, where n and N are the size of a given compressed string and the corresponding decompressed string, respectively. Our input strings are compressed by balanced straight line program (BSLP). We remark that BSLP has exponential compression, that is, N = O(2 ^{n}). Hence no decompress-then-test approaches can be better than our method in the worst case.

Original language | English |
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Title of host publication | Theory of Computing 2009 - Proceedings of the Fifteenth Computing: The Australasian Theory Symposium, CATS 2009 |

Volume | 94 |

Publication status | Published - 2009 |

Event | Theory of Computing 2009 - 15th Computing: The Australasian Theory Symposium, CATS 2009 - Wellington, New Zealand Duration: Jan 20 2009 → Jan 23 2009 |

### Other

Other | Theory of Computing 2009 - 15th Computing: The Australasian Theory Symposium, CATS 2009 |
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Country | New Zealand |

City | Wellington |

Period | 1/20/09 → 1/23/09 |

### Fingerprint

### All Science Journal Classification (ASJC) codes

- Computer Networks and Communications
- Computer Science Applications
- Hardware and Architecture
- Information Systems
- Software

### Cite this

*Theory of Computing 2009 - Proceedings of the Fifteenth Computing: The Australasian Theory Symposium, CATS 2009*(Vol. 94)

**Testing square-freeness of strings compressed by balanced straight line program.** / Matsubara, Wataru; Inenaga, Shunsuke; Shinohara, Ayumi.

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

*Theory of Computing 2009 - Proceedings of the Fifteenth Computing: The Australasian Theory Symposium, CATS 2009.*vol. 94, Theory of Computing 2009 - 15th Computing: The Australasian Theory Symposium, CATS 2009, Wellington, New Zealand, 1/20/09.

}

TY - GEN

T1 - Testing square-freeness of strings compressed by balanced straight line program

AU - Matsubara, Wataru

AU - Inenaga, Shunsuke

AU - Shinohara, Ayumi

PY - 2009

Y1 - 2009

N2 - In this paper we study the problem of deciding whether a given compressed string contains a square. A string x is called a square if x = zz and z = u k implies k = 1 and u = z. A string w is said to be square-free if no substrings of w are squares. Many efficient algorithms to test if a given string is square-free, have been developed so far. However, very little is known for testing square-freeness of a given compressed string. In this paper, we give an O(max(n 2, n log 2 N))-time O(n 2)-space solution to test square-freeness of a given compressed string, where n and N are the size of a given compressed string and the corresponding decompressed string, respectively. Our input strings are compressed by balanced straight line program (BSLP). We remark that BSLP has exponential compression, that is, N = O(2 n). Hence no decompress-then-test approaches can be better than our method in the worst case.

AB - In this paper we study the problem of deciding whether a given compressed string contains a square. A string x is called a square if x = zz and z = u k implies k = 1 and u = z. A string w is said to be square-free if no substrings of w are squares. Many efficient algorithms to test if a given string is square-free, have been developed so far. However, very little is known for testing square-freeness of a given compressed string. In this paper, we give an O(max(n 2, n log 2 N))-time O(n 2)-space solution to test square-freeness of a given compressed string, where n and N are the size of a given compressed string and the corresponding decompressed string, respectively. Our input strings are compressed by balanced straight line program (BSLP). We remark that BSLP has exponential compression, that is, N = O(2 n). Hence no decompress-then-test approaches can be better than our method in the worst case.

UR - http://www.scopus.com/inward/record.url?scp=84859645349&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84859645349&partnerID=8YFLogxK

M3 - Conference contribution

SN - 9781920682750

VL - 94

BT - Theory of Computing 2009 - Proceedings of the Fifteenth Computing: The Australasian Theory Symposium, CATS 2009

ER -