Two Algorithms in Search of a Type-System

  • Authors:
  • Norman Danner;James S. Royer

  • Affiliations:
  • Wesleyan University, Department of Mathematics and Computer Science, 06459, Middletown, CT, USA;Syracuse University, Department of Electrical Engineering and Computer Science, 13210, Syracuse, NY, USA

  • Venue:
  • Theory of Computing Systems - Special Issue: Computation and Logic in the Real World; Guest Editors: S. Barry Cooper, Elvira Mayordomo and Andrea Sorbi
  • Year:
  • 2009

Quantified Score

Hi-index 0.01

Visualization

Abstract

The authors’ $\mathsf{ATR}$programming formalism is a version of call-by-value $\mathsf{PCF}$under a complexity-theoretically motivated type system. $\mathsf{ATR}$programs run in type-2 polynomial-time and all standard type-2 basic feasible functionals are $\mathsf{ATR}$-definable ( $\mathsf{ATR}$types are confined to levels 0, 1, and 2). A limitation of the original version of $\mathsf{ATR}$is that the only directly expressible recursions are tail-recursions. Here we extend $\mathsf{ATR}$so that a broad range of affine recursions are directly expressible. In particular, the revised $\mathsf{ATR}$can fairly naturally express the classic insertion- and selection-sort algorithms, thus overcoming a sticking point of most prior implicit-complexity-based formalisms. The paper’s main work is in refining the original time-complexity semantics for $\mathsf{ATR}$to show that these new recursion schemes do not lead out of the realm of feasibility.