#sattools

SAT tools - some experiments around SAT formulas. Includes some formula generators and some algorithm implementations. The main goal of this project is to do statistics on executions of random algorithms (namely PPZ); for this we consider all possible random choices that the algorithm can do. Hence, the algorithms are explicitely and knowingly very inefficient.

I'm working on a research project around SAT - and I need a few tools around that, including simulation of algorithms I'm currently working on with different variants. I'm trying to get my code as generic and proper/usable as possible so that it may be used by other people!

Said algorithms are, however, much more on the theoretic/exponential bounds side - this is typically NOT a SAT solver that will solve anything "big" in any remotely reasonable time. We're talking Omega(2^n) time here. Don't expect better.

The PPZ algorithm was first described in the paper Satisfiability Coding Lemma by Paturi, Pudlak and Zane (see http://cm.bell-labs.com/who/francis/papers/focs97.ps). The "random" implementation is closest to the spirit of this algorithm - it picks a random permutation and a random codeword and tries them against the formula, retrying until it finds something or until it gets to a pre-set number of iterations. With the "full" implementation, one can check for all the permutations and all the codewords. With the "full with oracle" implementation, one can check for all the permutations and all the codewords, with the twist that, if both literals of a variable are satisfying, that variable is always set to 0. This implementation actually relies on a bruteforce solving of the assignments - it is NOT designed for any solving per se, but to get statistics and insight about the algorithm for different formulas.

The main executable is "sattools". The other executables (dimacs_tool, generate_sat_tool, ppz_random_tool and ppz_tool) are older tentatives and should be deprecated at some point.

Options for "sattools"

-h [ --help ]           Print help message
-n [ --n ] arg          Number of variables
-k [ --k ] arg          Arity of a clause
-f [ --file ] arg       Get formula from file
-r [ --random ] arg     Get random formula with given random range
-m [ --max ]            Get maximum formula from a set of assignments
-a [ --assignment ] arg List of assignments for -m
-i [ --interactive ]    Interactive mode
--bruteforce            Solve by bruteforce - warning, all case exponential 
                        time algorithm!
--ppzfull               Solve by full ppz - warning, all case 
                        superexponential time algorithm!
--ppzfulloracle         Solve by full ppz with oracle - warning, all case 
                        superexponential time algorithm!
--ppzrandom             Solve by random ppz - warning, worst case exponential
                        time algorithm!
-s [ --save ] arg       Save the formula in DIMACS format in given file. 
                        Default is save in 'formula.cnf'.

• Main executable
  • sattools.cpp: just invokes the command line parsing
  • commandline.cpp: command line parsing and dispatching
  • interactivemode.cpp: tiny console for formula creation and runs
• Basic structures
  • structs.h: small data structures that do not need any methods attached to them (namely, literals)
  • assignment.cpp: an assignment to a CNF formula
  • cnfclause.cpp: a CNF clause (disjunction of literals)
  • cnfformula.cpp: a CNF formula.
  • solvedcnf.cpp: a solved CNF formula (by bruteforce) - also allows checking for frozen variables.
  • ppz.cpp: PPZ algorithm implementations (full, full with oracle, random)
  • ppzrunstats.cpp: PPZ statistics for a run
  • userinput.cpp: manages user input from interactive mode/console
• Formula generators
  • satgenerator.cpp: parent class for the other generators
  • dimacsgenerator.cpp: reads a formula from a simplified DIMACS file (see http://www.satcompetition.org/2009/format-benchmarks2009.html)
  • maxsatgenerator.cpp: create a formula from a set of satisfying assignments by checking all possible clauses and inserting the ones that are compatible with the satisfying assignments.
  • randomsatgenerator.cpp: create a formula by generating all clauses and picking some of them according to the given probability
• Menus
  • formulacreationmenu.cpp: menu used by the interactive mode to create a formula
  • executionmenu.cpp: menu used to process the created formula in the interactive mode
• Miscellaneous tests and temporary executables
  • cnfclause_test.cpp, cnfformula_test.cpp: unit tests for cnfclause and cnfformula
  • dimacs_tool.cpp, generate_sat_tool.cpp,ppz_random_tool.cpp,ppz_tool.cpp: miscellaneous temporary executables used in previous versions instead of the generic "sattools" executable.
  • examples/satstats.cpp, examples/satstats2.cpp, examples/smallcover.cpp: miscellaneous "almost one-shot" bits of code that use the underlying structures of sattools to test some hypotheses.