ML typability is dexptime-complete

  • A. J. Kfoury
  • J. Tiuryn
  • P. Urzyczyn
Conference paper

DOI: 10.1007/3-540-52590-4_50

Part of the Lecture Notes in Computer Science book series (LNCS, volume 431)
Cite this paper as:
Kfoury A.J., Tiuryn J., Urzyczyn P. (1990) ML typability is dexptime-complete. In: Arnold A. (eds) CAAP '90. CAAP 1990. Lecture Notes in Computer Science, vol 431. Springer, Berlin, Heidelberg

Abstract

We carry out an analysis of typability of terms in ML. Our main result is that this problem is DEXPTIME-hard, where by DEXPTIME we mean DTIME\((2^{n^{O(1)} } )\). This, together with the known exponential-time algorithm that solves the problem, yields the DEXPTIME-completeness result. This settles an open problem of P. Kanellakis and J.C. Mitchell.

Part of our analysis is an algebraic characterization of ML typability in terms of a restricted form of semi-unification, which we identify as acyclic semi-unification. We prove that ML typability and acyclic semi-unification are log-space equivalent problems. We believe this result is of independent interest.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

Copyright information

© Springer-Verlag 1990

Authors and Affiliations

  • A. J. Kfoury
    • 1
  • J. Tiuryn
    • 2
  • P. Urzyczyn
    • 2
  1. 1.Dept of Computer ScienceBoston UniversityUSA
  2. 2.Institute of MathematicsUniversity of WarsawPoland

Personalised recommendations