 
   July 1, 1994                                                        SIS(1)
 
   stg_extract [-a] [-e] [-c]
 
     Takes the current network and extracts the state transition graph from
     it.
 
     If the -a option is not specified, the values on the latches are taken
     to be the start state, and every state reachable from the start state is
     explored.  This is the normal method of execution.
 
     If the -a option is specified, the state transition graph is extracted
     for all possible start states, provided the number of latches does not
     exceed 16.  This limitation cannot be overridden (there are too many
     states to store).
 
     Extraction of the STG could take an enormous amount of time.  If there
     are more than 16 latches in the network, stg_extract won't attempt to
     extract the STG.  This can be overridden with the -e option.
 
     At the end of stg_extract, a check is done to ensure that the behavior
     of the STG is consistent with that of the logic implementation.  This is
     done with symbolic simulation using BDDs, and could be expensive.
     stg_extract will not do this check for networks with more than 16
     latches or more than 500 transitions unless the -c option is given.
 
     Note: a sweep is done on the network before the STG is extracted.  This
     removes latches that do not fanout, so the sweep makes the extraction
     more efficient.
 
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