Limits on the number of diagrams
When using the offline version of MadGraph / MadEvent, there is no strict limit on the total number of Feynman diagrams generated by MadGraph. In practice, however, MadGraph may have difficulties to deal with more than approximatively 200k diagrams due to some memory constraints. When MadEvent is used for generating events, a empirical limit of 100k diagrams (10k per subprocess) should be respected.
When using the online version of MadGraph / MadEvent, the total number of diagram may be arbitrarily limited (to 10k or 40k, depending on the cluster) to avoid too long generations. This limit can always be removed for a specific process by sending an email to the cluster administrator.
-- Main.MichelHerquet - 02 Mar 2009