We recall the notion of regular closure of classes of languages. We present two important results. The rst one is that all languages which are in the regular closure of the class of deterministic (context-free) languages can be recognized in linear time. This is a non-trivial result, since this closure contains many inherently ambiguous languages. The second one is that the class of determinist...

We study one of the most basic online scheduling models, online one machine scheduling with delivery times where jobs arrive over time. We provide the rst randomized algorithm for this model, show that it is 1.55370-competitive and show that this analysis is tight. The best possible deterministic algorithm is 1:61803-competitive. Our algorithm is a distribution between two deterministic algorit...