, Volume 12, Issue 4, pp 361–371 | Cite as

Complexity of the unification algorithm for first-order expressions

  • M. Venturini Zilli


Rewriting and comparisons are the complexity aspects of the unification algorithm which are considered in this paper. A simplified version of Robinson's algorithm [2] is described where rewriting (already linear in the size of the input in [2]) is reduced by a constant factor and the number of comparisons (exponential in the size of the input in [2]) is bounded by a quantity polynomial of quadratic order in the size of the input.


Function Symbol General Substitution Code Number Quadratic Order Complexity Aspect 
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  1. [1]
    Robison, J. A.,A machine-oriented logic based on the resolution principle, J. Ass. Comput. Mach.12, (1965), 23–41.Google Scholar
  2. [2]
    Robinson, J. A.,Computational Logic: the unification computation, in Machine Intelligence6, 63–72.Google Scholar
  3. [3]
    Benturini Zilli M., Cerimele M. M.,COR: a program for proving theorems in first-order logic, (unpublished).Google Scholar
  4. [4]
    Venturini Zilli M.,Complessità dell'algoritmo di unificazione, in Proceedings of the Convegno di Informatica teorica, Mantova (1974), 87–96.Google Scholar

Copyright information

© Instituto di Elaborazione della Informazione del CNR 1976

Authors and Affiliations

  • M. Venturini Zilli
    • 1
  1. 1.IAC-CNRRoma

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