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Bring home now the book enPDFd the graph isomorphism problem its structural complexity 1st edition to be your sources when going to read. It can be your new collection to not only display in your… (More)

- Johannes Köbler, Osamu Watanabe
- SIAM J. Comput.
- 1998

- Johannes Köbler, Uwe Schöning, Jacobo Torán
- computational complexity
- 1992

We show that the graph isomorphism problem, is low for PP and for C=P, i.e., it does not provide a PP or C=P computation with any additional power when used as an oracle. Furthermore, we show that… (More)

- Johannes Köbler, Jochen Messner, Jacobo Torán
- Inf. Comput.
- 2003

A polynomial time computable function h : ! whose range is a set L is called a proof system for L. In this setting, anh-proof for x 2 L is just a stringw with h(w) = x. Cook and Reckhow defined this… (More)

- Birgit Jenner, Johannes Köbler, Pierre McKenzie, Jacobo Torán
- J. Comput. Syst. Sci.
- 2003

- Johannes Köbler, Uwe Schöning, Seinosuke Toda, Jacobo Torán
- Structure in Complexity Theory Conference
- 1989

The intractability of the complexity class NP has motivated the study of subclasses that arise when certain restrictions on the definition of NP are imposed. For example, the study of sparse sets in… (More)

- Vikraman Arvind, Johannes Köbler
- Theor. Comput. Sci.
- 2001

In this paper we extend a key result of Nisan and Wigderson NW94] to the nondeterministic setting: for all > 0 we show that if there is a language in E = DTIME(2 O(n)) that is hard to approximate by… (More)

- Johannes Köbler, Uwe Schöning, Klaus W. Wagner
- ITA
- 1987

Two hiérarchies of complexity classes are defined. Both, the différence hierarchy and the truth-table hierarchy for NP are located between NP as bottom class and A£. We give examples for complete… (More)

- Johannes Köbler, Sebastian Kuhnert, Bastian Laubner, Oleg Verbitsky
- SIAM J. Comput.
- 2011

We present a logspace algorithm for computing a canonical labeling, in fact, a canonical interval representation, for interval graphs. To achieve this, we compute canonical interval representations… (More)