CryptoMiniSat integrates a lot of advancements relative to MiniSat.
You can find these under the NEWS file. Here, we will explain how to
use the xor-clause and logging facilities of CryptoMiniSat:
* Xor-clauses. If you want to express a xor, e.g.
"var1 + var2 + !var3 = true"
then you simply need to put into the sat file the line:
"x1 2 -3 0". The "x" in
front of the line means that this is a xor-clause clause.
* Clause grouping. Usage: "-grouping" in command line. Used to give a
name to each and every clause. Useful if you wish to create meaningful
statistics. To use it, you must have after each and every clause a line
"c g GROUPNUM NAME".
Example:
161 18 20 -22 0
c g 11 nice name
161 -18 -20 0
c g 11 nice name
141 68 -66 74 0
c g 234 somewhat nicer name
These are three clauses. The first two belong to group 11, which has
the name "nice name". The third clause belongs to group 234, and is
named "somewhat nicer name". Grouping is important once you need to have
more than one clause to express the same concept. I.e. if you were describing
an equation in ANF (Algebraic Normal Form), you could easily give the same
group to the different clauses representing the same equation. You can find
examples of the usage in the "satfile" file under the "bulid" directory
* Variable naming. In the CNF file, you have to add a line describing the
name of each variable. The lines must follow the pattern
"c v VAR NAME"
for each variable. Example:
c v 36 sr[0][35] (real unknown)
This sets variable number 36 to be named "sr[0][35] (real unknown)".
You can find examples of this in the "satfile" under the "build"
directory. I personally add the definition of all variables at the
end of my CNF file.s
* Advanced statistics. The output of the sample satfile that is under
"/optimized/src/satfile" if running with statistics:
--------------
soos@charmille:$ ./cryptominisat -stats -grouping satfile
[..printed data..]
+===========================================================+
||********* STATS FOR THIS RESTART BEGIN ******************||
+===========================================================+
+-----------------------------------------------------------+
| No. times variable branched on |
|var var name no. times |
+-----------------------------------------------------------+
|54 sr[0][65](real unknown) 1608 |
|45 sr[0][49](real unknown) 1480 |
|82 sr[0][43](real unknown) 1461 |
|66 sr[0][54](real unknown) 1420 |
|195 sr[0][59](real unknown) 1407 |
|218 sr[0][69](real unknown) 1318 |
|88 sr[0][57](real unknown) 1307 |
|223 sr[0][51](real unknown) 1260 |
|426 sr[0][70](real unknown) 1201 |
|236 sr[0][47](real unknown) 1149 |
|83 sr[0][56](real unknown) 1118 |
|43 sr[0][45](real unknown) 1050 |
|387 sr[0][74](real unknown) 1014 |
|46 sr[0][72](real unknown) 1012 |
|378 sr[0][55](real unknown) 975 |
|349 sr[0][58](real unknown) 890 |
|9 sr[0][66](real unknown) 889 |
|279 sr[0][44](real unknown) 841 |
|108 sr[0][61](real unknown) 841 |
|401 sr[0][42](real unknown) 820 |
+-----------------------------------------------------------+
This list means that variable 54, which represents the 65th bit
in the shift register has been branched upon 1608 times during the
solving. This, by the way, is logical, as we were trying to solve the
state of the stream cipher, which is of course the shift register's
state.
The statistics also gives you the following for each restart
(minisat does re-starts every so often, these are the lines that
appear one after the other when you are running it):
+-----------------------------------------------------------+
| Advanced statistics |
+-----------------------------------------------------------+
|No. branches visited 15585 |
|Avg. branch depth 84.81 |
|No. decisions 32755 |
|No. propagations 1151570 |
|sum decisions on branches/no. branches |
| (in a given branch, what is the avg. |
| no. of decisions?) 8.518 |
|sum propagations on branches/no. branches |
| (in a given branch, what is the |
| avg. no. of propagations?) 76.29 |
+-----------------------------------------------------------+
You can see, for example, that 8.52 + 76.29 = 84.81 so things add up.
* "-randomize=XXX" randomizes the clause order and initial variable pick order.
You can measure how much time it takes for minisat on average to solve a
problem written down in a SAT file. Useful to calculate average speed of a
given problem instance. Just run the problem with multiple "-randomize=xx"
numbers and make the average.
* If you create a directory "proofs", and then you execute
"./minisat -proof-log -grouping satfile"
then CryptoMiniSat produces a set of files, named "NUM-proofX.dot" in the
"proofs" directory, where NUM is a fixed number for a given run, and X is
the restart number. For the example "satfile" under the "build" directory:
$ ls proofs/
7491-proof0.dot
7491-proof1.dot
7491-proof2.dot
[...]
First you need to get graphviz (free software, available form
http://www.graphviz.org/Download..php for both windows and linux). If you
now issue "dot -Tsvg 7491-proof1.dot > proof1.svg" and wait a couple of
minutes, you get a file "proof1.svg" that contains what happened at the 1st
restart (which is not really a restart, it's the first run: the 0th restart
is the inserting of clauses). This SVG file is included into this email
(zipped). You can view it only with a very good SVG-reader, like the
free-software inkscape ( http://www.inkscape.org/download/?lang=en ),
available under windows and linux.
* There is an option to have a LOT of debugging output from CryptoMiniSat. To
turn it on, define VERBOSE_DEBUG. See the "INSTALL" file how to do this.
After re-compilation, run CryptoMiniSat as usual. This will give you a LOT
of information regarding what happens inside CryptoMiniSat. Propagations,
cancellations, conflicts, conflict clauses, etc. To handle the amount of
information, I suggest you to run CryptoMiniSat as:
"./cryptominisat satfile > debug.txt"
and then open the "debug.txt" with your favourite text editor.
(I use "less" if the file is gigabyte-sized files)
