76 citations · 440 across the 53 of their papers we have counts for
Showing 2009 · math.LOShow all
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math.LO2009★ 2 cited
A rigid cone in the truth-table degrees with jump
Bjørn Kjos-Hanssen
The automorphism group of the truth-table degrees with order and jump is fixed on the set of degrees above the fourth jump of 0.
math.LO2009★ 76 cited
Kolmogorov complexity and the Recursion Theorem
Bjørn Kjos-Hanssen, Wolfgang Merkle, Frank Stephan
Several classes of DNR functions are characterized in terms of Kolmogorov complexity. In particular, a set of natural numbers A can wtt-compute a DNR function iff there is a nontri…
math.LO2009★ 5 cited
Lattice initial segments of the Turing degrees
Bjørn Kjos-Hanssen
We characterize the isomorphism types of principal ideals of the Turing degrees below 0' that are lattices as the lattices with a Sigma-0-3 presentation, by showing that each Sigma…