1 This is the 64 bit version of zchaff.
4 Fixed the inefficiency bug in zverify_df. Thanks to Allen Van Gelder and
7 [2004.11.15 Simplified]
8 This is just a simplified version of 2004.5.13. Many portions of dead
9 codes are removed. Some of codes are re-written and re-formatted for
10 easy reading. You might experience a little speedup. Please switch back
11 to 2004.5.13 if the functionalities you need are removed in the simplified
15 Some performace update. This is the version we used for SAT04 competition.
16 Please consult our website for the detailed description.
20 1. Various bugs in add_clause_incr(). We would like to thank Alexander
21 Smith from University of Toronto for his suggestion and experiments on
24 3. unset_force_terminate added.
28 1. Compile under g++ 3.3 and above
29 2. Assertion error for certain instances in core extraction
30 3. A typo in run_till_fix. Now it takes the second argument as the max
31 number of iterations to run as intended.
34 Fixes in this release:
35 1. Bug fixed for time overflow after 2147 seconds.
36 2. The Perl script run_till_fix is updated such that it works for cnf
37 files located in other directory.
38 3. zverify_df.cpp now also verifies the conflict clause given in
39 resolve_trace with the one constructed by zverify itself using the
40 information given in resolve_trace.
42 NOTE: If your code is in C instead of C++, please use SAT_C.h instead of
43 SAT.h as the header file.
45 This is a new (as of June, 2003) release of zchaff, a SAT solver from
46 Princeton University. The main difference between this one and the
47 previous (2001.2.17) version are listed in the following:
48 1. This version of zchaff has incremental SAT solving capability
49 In practice, many SAT instances are related in the sense that they only
50 differ in a small number of clauses. Zchaff can solve a set of
51 such instances incrementally, leveraging the knowledge (clauses) learned
52 from previous runs to help current runs. This feature can only be invoked
53 through the functional call interface. Please read SAT.h for more
54 information about assigning clauses with Group IDs and how to delete
55 clause or add clauses by groups.
58 2. This version of zchaff is certifiable
59 Now zchaff can produce a verifiable trace that can be checked by a third
60 party checker. To invoke this, modify zchaff_solver.cpp and uncomment
61 #define VERIFY_ON and compile again. Now zchaff will produce a trace
62 called resolution_trace after each run and this can be checked by
63 zverify_bf or zverify_df, which are two checkers based on breadth-first
64 and depth-first search.
67 3. This version of zchaff can produce an unsatisfiable core from an
68 unsatisifable formula Unsatisfiable core extraction can be useful for
69 some applications. This version of zchaff implement the idea presented
70 in our SAT 2003 paper about extracting unsat cores.
72 4. This version can compile under gcc 3.x.
74 5. This version fixed a couple of serious bugs in the previous version.
75 (But may have introduced other bugs :().
79 Use "make" to compile, or "make all" to compile zchaff with extra utilities
80 (e.g. core extractor, verifier). It should work without any problem
81 under Linux, Cygwin or Solaris.
83 To compile a native Windows executable, Open Visual Studio .Net, create
84 a project, and add these files into the project:
86 zchaff_cpp_wrapper.cpp (this can be obtained by rename
87 zchaff_wrapper.wrp to zchaff_cpp_wrapper.cpp and delete all occurance of
88 "EXTERN" in the file.)
94 Also, modify files that contain headers "sys/*.h". Delete those troublesome
95 headers, replace them with "#include <time.h>", and replace the code for
96 function get_cpu_time() with:
98 double get_cpu_time(void) {
99 return (double)clock()/(double)(CLOCKS_PER_SEC);
101 This function will overflow after 2147 seconds. So the reported time
102 may not be correct. This is a temporary solution and hopefully we will fix it in
105 MSVC will report a lot of warnings. Hopefully none is serious. :(. As
106 you suspected, zchaff is not tested under native Windows enviroment.
107 But anyway, this is the hack.
110 the main executable is zchaff. The command line is
111 zchaff CNF_FILE [TimeLimit]
112 Other executables will print out a help info when executed with no
115 run_till_fix can obtain a small core by iteratively run core extraction.
117 VERIFY_ON in zchaff_solver.cpp when compile.
119 For any questions or bug reports, please send email to
120 Yogesh Mahajan at yogism@Princeton.EDU
124 The SAT Group at Princeton University