This method computes an estimate of GVT for the LP. The LP calls this method at the end of each simulation cycle, and sends a message to the central manager under the conditions mandated by the PGVT algorithm. Essentially, the GVTManager for an LP has an array of pointers to the simulation objects local to the LP, and it walks through this array ``asking'' the the simulation objects to calculate their estimates, and the minimum of these estimates is the new LGVT value. Only objects that ran in the last simulation cycle or have something ready to execute are considered in the LGVT calculation.