diff options
| -rw-r--r-- | src/base/io/io.c | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/src/base/io/io.c b/src/base/io/io.c index 8cc78623..49e1def1 100644 --- a/src/base/io/io.c +++ b/src/base/io/io.c @@ -2248,6 +2248,17 @@ usage: fprintf( pAbc->Err, "\t-v : toggle printing verbose information [default = %s]\n", fVerbose? "yes" : "no" ); fprintf( pAbc->Err, "\t-h : print the help massage\n" ); fprintf( pAbc->Err, "\tfile : the name of the file to write\n" ); + fprintf( pAbc->Err, "\n" ); + fprintf( pAbc->Err, "\t CNF variable mapping rules:\n" ); + fprintf( pAbc->Err, "\n" ); + fprintf( pAbc->Err, "\t Assume CNF has N variables, with variable IDs running from 0 to N-1.\n" ); + fprintf( pAbc->Err, "\t Variable number 0 is not used in the CNF.\n" ); + fprintf( pAbc->Err, "\t Variables 1, 2, 3,... <nPOs> represent POs in their natural order.\n" ); + fprintf( pAbc->Err, "\t Variables N-<nPIs>, N-<nPIs>+1, N-<nPIs>+2, ... N-1, represent PIs in their natural order.\n" ); + fprintf( pAbc->Err, "\t The internal variables are ordered in a reverse topological order from outputs to inputs.\n" ); + fprintf( pAbc->Err, "\t That is, smaller variable IDs tend to be closer to the outputs, while larger\n" ); + fprintf( pAbc->Err, "\t variable IDs tend to be closer to the inputs. It was found that this ordering\n" ); + fprintf( pAbc->Err, "\t leads to faster SAT solving for hard UNSAT CEC problems.\n" ); return 1; } |