Gröbner Bases in Type Theory

  • Authors:
  • Thierry Coquand;Henrik Persson

  • Affiliations:
  • -;-

  • Venue:
  • TYPES '98 Selected papers from the International Workshop on Types for Proofs and Programs
  • Year:
  • 1998

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Abstract

We describe how the theory of Gröbner bases, an important part of computational algebra, can be developed within Martin-Löf's type theory. In particular, we aim for an integrated development of the algorithms for computing Gröbner bases: we want to prove, constructively in type theory, the existence of Gröbner bases and from such proofs extract the algorithms. Our main contribution is a reformulation of the standard theory of Gröbner bases which uses generalised inductive definitions. We isolate the main non-constructive part, a minimal bad sequence argument, and use the open induction principle [Rao88,Coq92] to interpret it by induction. This leads to short constructive proofs of Dickson's lemma and Hilbert's basis theorem, which are used to give an integrated development of Buchberger's algorithm. An important point of this work is that the elegance and brevity of the original proofs are maintained while the new proofs also have a direct constructive content. In the appendix we present a computer formalisation of Dickson's lemma and an abstract existence proof of Gröbner bases.