Isotropy of Algebraic Theories

  title={Isotropy of Algebraic Theories},
  author={Pieter J. W. Hofstra and Jason Parker and P. Scott},
  journal={Electr. Notes Theor. Comput. Sci.},
Abstract To every small category or topos one may associate its isotropy group, which is an algebraic invariant capturing information about the behaviour of automorphisms. We investigate this invariant in the particular situation of algebraic theories, thus obtaining a group-theoretic invariant of algebraic theories. This invariant encodes a notion of inner automorphism relative to the theory. Our main technical result is a syntactic characterization of the isotropy group of an algebraic theory… Expand

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