2-Opt is probably the most basic and widely used local search
heuristic for the TSP. This heuristic achieves amazingly good
results on "real world" Euclidean instances both with respect to
running time and approximation ratio. There are numerous
experimental studies on the performance of 2-Opt. However, the
theoretical knowledge about ... more >>>

Strategic games may exhibit symmetries in a variety of ways. A common aspect of symmetry, enabling the compact representation of games even when the number of players is unbounded, is that players cannot (or need not) distinguish between the other players. We define four classes of symmetric games by considering ... more >>>

<p> We study the question of the existence of non-mitotic sets in NP. We show under various hypotheses that:</p>
<ul>
<li>1-tt-mitoticity and m-mitoticity differ on NP.</li>
<li>1-tt-reducibility and m-reducibility differ on NP.</li>
<li>There exist non-T-autoreducible sets in NP (by a result from Ambos-Spies, these sets are neither ... more >>>