3. Filtered databases:

Table 8: PerfectClub: Numbers of exceptions in filtered database

	PerfectClub
timeout = 2 minutes	#overflows	#timeouts	#operations
JANUS 64-bit	0	0	1310
$C^3$ Simplex 64-bit	2	0	1310
$C^3$ Fourier-Motzkin	0	0	1310
$C^3$ Double Description	0	407	1310

6_tab:PerfectClub_satisfiability_exception_filter shows that with PerfectClub filtered databases, JANUS 64-bit, Fourier-Motzkin and Double Description method has no overflow exception, whereas $C^3$ Simplex has only two overflows. Only $C^3$ Double Description method raises as many as $407$ timeout exceptions that may block our analysis.

It is however very different with SPEC95, filtered database , as shown in 6_tab:SPEC95_satisfiability_exception_filter: $C^3$ Simplex has $3714$ overflow exceptions, $727$ more than JANUS 64-bit. $C^3$ Fourier Motzkin method has only $8$ overflows and $626$ timeout exception. And the winner in this case is surprisingly the $C^3$ Double Description method, with only $22$ overflows and no timeout exception. To understand this difference, we decided to investigate these two filtered databases.

Table 9: SPEC95: Numbers of exceptions in filtered database

	SPEC95
timeout = 2 minutes	#overflows	#timeouts	#operations
JANUS 64-bit	2987	0	4676
$C^3$ Simplex 64-bit	3714	0	4676
$C^3$ Fourier-Motzkin	8	626	4676
$C^3$ Double Description	22	0	4676