has characteristic uses Gillespie direct algorithm approximate solution nested stochastic simulation algorithm 2011-06-02 http://identifiers.org/pubmed/16321076 AZ This multiscale method is a small modification of the Gillespie's direct method [http://identifiers.org/biomodels.kisao/KISAO_0000029], in the form of a nested SSA, with inner loops for the fast reactions, and outer loop for the slow reactions. The number of groups can be more than two, and the grouping into fast and slow variables can be done dynamically in an adaptive version of the scheme. nested SSA accelerated stochastic simulation algorithm