The Gallai-Milgram theorem says that the vertex set of any digraph with stability number k can be partitioned into k directed paths. In 1990, Hahn and Jackson conjectured that this theorem is best possible in the following strong sense. For each positive integer k, there is a digraph D with stability number k such that deleting the vertices of any k− 1 directed paths in D leaves a digraph with ...

Evaluation of linear ozone photochemistry parametrizations in a stratosphere-troposphere data assimilation system A. J. Geer, W. A. Lahoz, D. R. Jackson, D. Cariolle, and J. P. McCormack Data Assimilation Research Centre (DARC), University of Reading, Reading, UK Now at European Centre for Medium-Range Weather Forecasts (ECMWF), Reading, UK Met Office, Exeter, UK Centre Européen de Recherche et...

In a recent article, J. D. Kiernan-Lewis has claimed that "it is evident that Nathan Oaldander has failed to understand both the analogy and the ontological point of the argument against tenselessness." The argument, which he believes is implicit in Prior's classic paper "Thank Goodness That's Over," is analogous to the arguments by Thomas Nagel and Frank Jackson against physicalism. Thus, Kier...