### Abstract

The technique of speeding up access into search structures by maintaining fingers that point to various locations of the search structure is considered. The problem of choosing, in a large search structure, locations at which to maintain fingers is treated. In particular, a server problem in which k servers move along a line segment of length m, where m is the number of keys in the search structure, is addressed. Since fingers may be arbitrarily copied, a server is allowed to jump, or fork, to a location currently occupied by another server. Online algorithms are presented and their competitiveness analyzed. It is shown that the case in which k = 2 behaves differently from the case in which k ≥ 3, by showing that there is a four-competitive algorithm for k = 2 that never forks its fingers. For k ≥ 3, it is shown that any online algorithm that does not fork its fingers can be at most Ω(m^{1/2})-competitive. The main result is that for k = 3 there is an online algorithm that forks and is constant competitive (independent of m, the size of the search structure). The algorithm is simple and implementable.

Original language | English (US) |
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Title of host publication | Annual Symposium on Foundations of Computer Science - Proceedings |

Publisher | Publ by IEEE |

Pages | 480-489 |

Number of pages | 10 |

Volume | 2 |

State | Published - 1990 |

Event | Proceedings of the 31st Annual Symposium on Foundations of Computer Science - St. Louis, MO, USA Duration: Oct 22 1990 → Oct 24 1990 |

### Other

Other | Proceedings of the 31st Annual Symposium on Foundations of Computer Science |
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City | St. Louis, MO, USA |

Period | 10/22/90 → 10/24/90 |

### Fingerprint

### ASJC Scopus subject areas

- Hardware and Architecture

### Cite this

*Annual Symposium on Foundations of Computer Science - Proceedings*(Vol. 2, pp. 480-489). Publ by IEEE.

**Online algorithms for finger searching.** / Cole, Richard; Raghunathan, Arvind.

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

*Annual Symposium on Foundations of Computer Science - Proceedings.*vol. 2, Publ by IEEE, pp. 480-489, Proceedings of the 31st Annual Symposium on Foundations of Computer Science, St. Louis, MO, USA, 10/22/90.

}

TY - GEN

T1 - Online algorithms for finger searching

AU - Cole, Richard

AU - Raghunathan, Arvind

PY - 1990

Y1 - 1990

N2 - The technique of speeding up access into search structures by maintaining fingers that point to various locations of the search structure is considered. The problem of choosing, in a large search structure, locations at which to maintain fingers is treated. In particular, a server problem in which k servers move along a line segment of length m, where m is the number of keys in the search structure, is addressed. Since fingers may be arbitrarily copied, a server is allowed to jump, or fork, to a location currently occupied by another server. Online algorithms are presented and their competitiveness analyzed. It is shown that the case in which k = 2 behaves differently from the case in which k ≥ 3, by showing that there is a four-competitive algorithm for k = 2 that never forks its fingers. For k ≥ 3, it is shown that any online algorithm that does not fork its fingers can be at most Ω(m1/2)-competitive. The main result is that for k = 3 there is an online algorithm that forks and is constant competitive (independent of m, the size of the search structure). The algorithm is simple and implementable.

AB - The technique of speeding up access into search structures by maintaining fingers that point to various locations of the search structure is considered. The problem of choosing, in a large search structure, locations at which to maintain fingers is treated. In particular, a server problem in which k servers move along a line segment of length m, where m is the number of keys in the search structure, is addressed. Since fingers may be arbitrarily copied, a server is allowed to jump, or fork, to a location currently occupied by another server. Online algorithms are presented and their competitiveness analyzed. It is shown that the case in which k = 2 behaves differently from the case in which k ≥ 3, by showing that there is a four-competitive algorithm for k = 2 that never forks its fingers. For k ≥ 3, it is shown that any online algorithm that does not fork its fingers can be at most Ω(m1/2)-competitive. The main result is that for k = 3 there is an online algorithm that forks and is constant competitive (independent of m, the size of the search structure). The algorithm is simple and implementable.

UR - http://www.scopus.com/inward/record.url?scp=0025530516&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0025530516&partnerID=8YFLogxK

M3 - Conference contribution

AN - SCOPUS:0025530516

VL - 2

SP - 480

EP - 489

BT - Annual Symposium on Foundations of Computer Science - Proceedings

PB - Publ by IEEE

ER -