Structure of proofs and the complexity of cut elimination

  • Authors:
  • Wenhui Zhang

  • Affiliations:
  • Laboratory of Computer Science, Institute of Software, Chinese Academy of Sciences, Beijing, China

  • Venue:
  • Theoretical Computer Science
  • Year:
  • 2006

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Abstract

The importance of the structure of cut-formulas with respect to proof length and proof depth has been studied in various occasions. It has been illustrated that a quantifier may be more powerful than a binary connective in cut-formulas with respect to the reduction (or increase) of proof length and proof depth, and a sequence of quantifiers of the same type (existential or universal) may be less powerful than a sequence of quantifiers of alternating types. This paper provides a refined view on cut-elimination through an analysis of the structure of proofs, brings new insight into the relation between cut-formulas and short proofs, and illustrates that a mixture of quantifiers and binary connectives could be important for achieving the maximal benefit of cut-formulas for obtaining short proofs.