On the complement of one complexity class in another

  • Diana Schmidt
Section I: Complexity
Part of the Lecture Notes in Computer Science book series (LNCS, volume 171)


We investigate the diagonalization theorems in [7] (Theorem 23), [3] (Theorem 6) and [10] (main Theorem) and show that they can be strengthened so as to be applicable to most complexity classes, not just to those closed under polynomial-time reducibility. Thus the applications in [7], [3] and [10] (e.g. PPNP\P is not recursively presentable) are not peculiar to P, NP, PSPACE etc.; rather, they are examples of properties common to almost all "reasonable" complexity classes.


Turing Machine Complexity Class Regular Language Finite Variation Polynomial Hierarchy 
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Copyright information

© Springer-Verlag Berlin Heidelberg 1984

Authors and Affiliations

  • Diana Schmidt
    • 1
  1. 1.Institut für Informatik I, Zirkel 275 Karlsruhe 1Federal Republic of Germany

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