/**
\brief Finds the maximal number of assumptions that can be satisfied.
An assumption is any formula preceeded with the :assumption keyword.
"Hard" constraints can be supported by using the :formula keyword.
Input: file in SMT-LIB format, and MaxSAT algorithm to be used: 0 - Naive, 1 - Fu&Malik's algo.
Output: the maximum number of assumptions that can be satisfied.
*/
int smtlib_maxsat(char * file_name, int approach)
{
Z3_context ctx;
Z3_solver s;
unsigned num_hard_cnstrs, num_soft_cnstrs;
Z3_ast * hard_cnstrs, * soft_cnstrs;
unsigned result = 0;
ctx = mk_context();
s = Z3_mk_solver(ctx);
Z3_parse_smtlib_file(ctx, file_name, 0, 0, 0, 0, 0, 0);
hard_cnstrs = get_hard_constraints(ctx, &num_hard_cnstrs);
soft_cnstrs = get_soft_constraints(ctx, &num_soft_cnstrs);
switch (approach) {
case NAIVE_MAXSAT:
result = naive_maxsat(ctx, s, num_hard_cnstrs, hard_cnstrs, num_soft_cnstrs, soft_cnstrs);
break;
case FU_MALIK_MAXSAT:
result = fu_malik_maxsat(ctx, s, num_hard_cnstrs, hard_cnstrs, num_soft_cnstrs, soft_cnstrs);
break;
default:
/* Exercise: implement your own MaxSAT algorithm.*/
error("Not implemented yet.");
break;
}
free_cnstr_array(hard_cnstrs);
free_cnstr_array(soft_cnstrs);
return result;
}
int main(int argc, const char **argv) {
/* Create a Z3 context to contain formulas */
Z3_config cfg = Z3_mk_config();
Z3_context ctx = iz3_mk_context(cfg);
Z3_set_error_handler(ctx, throw_z3_error);
/* Make some constraints, by parsing an smtlib formatted file given as arg 1 */
try {
Z3_parse_smtlib_file(ctx, argv[1], 0, 0, 0, 0, 0, 0);
}
catch(const z3_error &err){
std::cerr << "Z3 error: " << Z3_get_error_msg(err.c) << "\n";
std::cerr << Z3_get_smtlib_error(ctx) << "\n";
return(1);
}
/* Get the constraints from the parser. */
int num = Z3_get_smtlib_num_formulas(ctx);
if(num == 0){
std::cerr << "iZ3 error: File contains no formulas.\n";
return 1;
}
Z3_ast *constraints = (Z3_ast *)malloc(num * sizeof(Z3_ast));
int i;
for (i = 0; i < num; i++)
constraints[i] = Z3_get_smtlib_formula(ctx, i);
/* if we get only one formula, and it is a conjunction, split it into conjuncts. */
if(num == 1){
Z3_app app = Z3_to_app(ctx,constraints[0]);
Z3_func_decl func = Z3_get_app_decl(ctx,app);
Z3_decl_kind dk = Z3_get_decl_kind(ctx,func);
if(dk == Z3_OP_AND){
int nconjs = Z3_get_app_num_args(ctx,app);
if(nconjs > 1){
std::cout << "Splitting formula into " << nconjs << " conjuncts...\n";
num = nconjs;
constraints = new Z3_ast[num];
for(int k = 0; k < num; k++)
constraints[k] = Z3_get_app_arg(ctx,app,k);
}
}
}
/* print out the result for grins. */
// Z3_string smtout = Z3_benchmark_to_smtlib_string (ctx, "foo", "QFLIA", "sat", "", num, constraints, Z3_mk_true(ctx));
// Z3_string smtout = Z3_ast_to_string(ctx,constraints[0]);
// Z3_string smtout = Z3_context_to_string(ctx);
// puts(smtout);
// iz3_print(ctx,num,constraints,"iZ3temp.smt");
/* Make room for interpolants. */
Z3_ast *interpolants = (Z3_ast *)malloc((num-1) * sizeof(Z3_ast));
/* Make room for the model. */
Z3_model model = 0;
/* Call the prover */
Z3_lbool result = iz3_interpolate(ctx, num, constraints, interpolants, &model);
switch (result) {
/* If UNSAT, print the interpolants */
case Z3_L_FALSE:
printf("unsat, interpolants:\n");
for(i = 0; i < num-1; i++)
printf("%s\n", Z3_ast_to_string(ctx, interpolants[i]));
std::cout << "Checking interpolants...\n";
const char *error;
if(iZ3_check_interpolant(ctx, num, constraints, 0, interpolants, &error))
std::cout << "Interpolant is correct\n";
else {
std::cout << "Interpolant is incorrect\n";
std::cout << error << "\n";
}
break;
case Z3_L_UNDEF:
printf("fail\n");
break;
case Z3_L_TRUE:
printf("sat\n");
printf("model:\n%s\n", Z3_model_to_string(ctx, model));
break;
}
/* Delete the model if there is one */
if (model)
Z3_del_model(ctx, model);
/* Delete logical context (note, we call iz3_del_context, not
Z3_del_context */
iz3_del_context(ctx);
return 0;
}
