NNF_NODE var2nnf(Var* var, NnfManager* nnf_manager) {
Lit* plit = sat_pos_literal(var);
Lit* nlit = sat_neg_literal(var);
if(sat_implied_literal(plit)) return nnf_literal2node(plit,nnf_manager);
else if(sat_implied_literal(nlit)) return nnf_literal2node(nlit,nnf_manager);
else return ONE_NNF_NODE;
}
BOOLEAN sat_check_subsumed_clause(const Clause* clause) {
c2dSize size = sat_clause_size(clause);
for (c2dSize i = 0; i < size; i++) {
Lit* lit = vector_get(&clause->lits, i);
if (sat_implied_literal(lit))
return 1;
}
return 0;
}
//applies unit resolution to the cnf of sat state
//returns 1 if unit resolution succeeds, 0 if it finds a contradiction
BOOLEAN sat_unit_resolution(SatState* sat_state) {
BOOLEAN more = 1;
while (more) {
more = 0;
for (c2dSize i = vector_size(&sat_state->q); i >= 1; i--) {
Clause* clause = vector_get(&sat_state->q, i - 1);
clause->subsumed = sat_check_subsumed_clause(clause);
if (sat_subsumed_clause(clause)) {
vector_erase(&sat_state->q, i - 1);
continue;
}
BOOLEAN flag = 0;
c2dSize pos;
for (c2dSize j = 0; j < sat_clause_size(clause); j++) {
Lit* lit = vector_get(&clause->lits, j);
if (!sat_implied_literal(sat_opp_literal(lit))) {
flag++;
pos = j;
if (flag == 2)
break;
}
}
if (flag == 0) {
sat_state->ac = malloc(sizeof(Clause));
vector_init(&sat_state->ac->lits);
sat_state->ac->subsumed = 0;
sat_state->ac->mark = 0;
if (vector_size(&sat_state->ds) > 0) {
for (c2dSize j = 0; j < sat_var_count(sat_state); j++) {
Var* var = vector_get(&sat_state->vars, j);
var->u = var->level <= 1;
}
sat_get_assert_clause(sat_state, sat_state->ac, clause->index - 1, 0,
vector_size(&sat_state->s) - 1);
}
return 0;
}
if (flag == 1) {
Lit* lit = vector_get(&clause->lits, pos);
lit->implied = 1;
lit->locate = clause->index - 1;
lit->var->level = vector_size(&sat_state->ds) + 1;
vector_push(&sat_state->il, lit);
vector_push(&sat_state->s, lit);
clause->subsumed = 1;
vector_erase(&sat_state->q, i - 1);
more = 1;
}
}
}
return 1;
}
static BOOLEAN evaluate_delta(SatState* sat_state, Lit** pending_list, unsigned long num_pending_lit){
BOOLEAN fails =0;
#ifdef DEBUG
printf("Evaluate delta loop: %ld at pending lit %ld \n",num_pending_lit, pending_list[num_pending_lit-1]->sindex );
#endif
// just for the sake of this function but will be reset if contradiction happens
for(unsigned long i =0; i < num_pending_lit; i++){
Lit* pending_lit = pending_list[i];
pending_lit->decision_level = sat_state->current_decision_level;
if(pending_lit->sindex <0){
pending_lit->LitValue = 0;
pending_lit->LitState = 1;
Lit* opposite_Lit = sat_literal_var(pending_lit)->posLit;
opposite_Lit->LitValue = 0;
opposite_Lit->LitState = 1;
opposite_Lit->decision_level = pending_lit->decision_level;
}
else if(pending_lit->sindex >0){
pending_lit->LitValue = 1;
pending_lit->LitState = 1;
Lit* opposite_Lit = sat_literal_var(pending_lit)->negLit;
opposite_Lit->LitValue = 1;
opposite_Lit->LitState = 1;
opposite_Lit->decision_level = pending_lit->decision_level;
}
}
for(unsigned long i=0; i<sat_state->num_clauses_in_delta; i++){
Clause* clause = &sat_state->delta[i];
//check clause
BOOLEAN contradiction_found = 1;
for(unsigned long k = 0; k<clause->num_literals_in_clause;k++){
//check if the literal is asserted or not yet set
if(sat_is_asserted_literal(clause->literals[k]) || (!sat_implied_literal(clause->literals[k]) )){
contradiction_found = 0;
break; //don't check the other literals of the clause
}
} // for all literals in a clause
if(contradiction_found == 1){
fails = 1;
sat_state->conflict_clause = clause;
#ifdef DEBUG
printf("In Evaluate Delta: \t");
print_clause(clause);
#endif
// for(unsigned long j = 0; j < num_pending_lit; j++){
// Lit* pending_lit = pending_list[j];
// pending_lit->LitValue = 'u';
// pending_lit->LitState = 0;
// //SALMA added this
// pending_lit->decision_level = 0;
// if(pending_lit->sindex <0){
// Lit* opposite_Lit = sat_literal_var(pending_lit)->posLit;
// opposite_Lit->LitValue = 'u';
// opposite_Lit->LitState = 0;
// //SALMA added this
// opposite_Lit->decision_level = 0;
// }else{
// Lit* opposite_Lit = sat_literal_var(pending_lit)->negLit;
// opposite_Lit->LitValue = 'u';
// opposite_Lit->LitState = 0;
// //SALMA added this
// opposite_Lit->decision_level = 0;
// }
//
// }
break;
}
}//end of for loop on clauses in delta
#ifdef DEBUG
printf("Contradiction_found = %d\n",fails);
#endif
return fails;
}
static BOOLEAN evaluate_current_assignment(SatState* sat_state, Lit** pending_list, unsigned long num_pending_lit){
#ifdef DEBUG
printf("Evaluate the current assignment\n");
#endif
BOOLEAN fails = 0;
// just for the sake of this function but will be reset if contradiction happens
for(unsigned long i =0; i<num_pending_lit; i++){
Lit* pending_lit = pending_list[i];
if(pending_lit->sindex <0){
pending_lit->LitValue = 0;
pending_lit->LitState = 1;
}
else if(pending_lit->sindex >0){
pending_lit->LitValue = 1;
pending_lit->LitState = 1;
}
}
Lit** decisions = sat_state->decisions;
//now I have the current decision and the pending list
// instead of merging the two list in one list just pass by each one
for(unsigned long i =0; i<sat_state->num_literals_in_decision; i++){
#ifdef DEBUG
printf("In the decision literals loop: current literal %ld \n", decisions[i]->sindex);
#endif
Var* corresponding_var = sat_literal_var(decisions[i]);
unsigned long* decision_clause_list = corresponding_var->list_clause_of_variables;
for(unsigned long j=0; j<corresponding_var->num_of_clauses_of_variables; j++){
Clause* clause = sat_index2clause(decision_clause_list[j], sat_state);
//check clause
for(unsigned long k = 0; k<clause->num_literals_in_clause;k++){
//check if the literal is asserted or not yet set
if(sat_is_asserted_literal(clause->literals[k]) || (!sat_implied_literal(clause->literals[k]) )){
break; //don't check the other literals of the clause
}
else if(k== clause->num_literals_in_clause-1){ // I reached the end of the loop with no break (contradicted clause)
fails = 1;
sat_state->conflict_clause = clause;
// reset the pending list
for(unsigned long i =0; i<num_pending_lit; i++){
Lit* pending_lit = pending_list[i];
pending_lit->LitValue = 'u';
pending_lit->LitState = 0;
}
return fails;
}
} // for all literals in a clause
} // for all clauses for this variable
}// for all variables in decision list
//repeat the same for pending list
for(unsigned long i =0; i< num_pending_lit; i++){
#ifdef DEBUG
printf("In the pending literals loop: current literal %ld \n", pending_list[i]->sindex);
#endif
Var* corresponding_var = sat_literal_var(pending_list[i]);
unsigned long* pending_clause_list = corresponding_var->list_clause_of_variables;
for(unsigned long j=0; j<corresponding_var->num_of_clauses_of_variables; j++){
Clause* clause = sat_index2clause(pending_clause_list[j], sat_state);
//check clause
for(unsigned long k = 0; k<clause->num_literals_in_clause;k++){
//check if the literal is asserted or not yet set
if(sat_is_asserted_literal(clause->literals[k]) || (!sat_implied_literal(clause->literals[k]) )){
break; //don't check the other literals of the clause
}
else if(k== clause->num_literals_in_clause-1){ // I reached the end of the loop with no break (contradicted clause)
fails = 1;
sat_state->conflict_clause = clause;
// reset the pending list
for(unsigned long i =0; i<num_pending_lit; i++){
Lit* pending_lit = pending_list[i];
pending_lit->LitValue = 'u';
pending_lit->LitState = 0;
}
return fails;
}
} // for all literals in a clause
} // for all clauses for this variable
}// for all variables in pending list
//TODO: check do i have to unset all the literals in the pending list
#ifdef DEBUG
if(fails == 1){
printf("Contradiction happens in evaluating clauses in the pending list\n");
}
#endif
return fails;
}
Var* sat_index2var(c2dSize index, const SatState* sat_state) {
ASSERT_TEST(index>=1 && index<=sat_var_count(sat_state)); //index range test
return sat_state->variables[index-1];
}
//returns the index of a variable
c2dSize sat_var_index(const Var* var) {
return var->index;
}
//returns the variable of a literal
Var* sat_literal_var(const Lit* lit) {
return lit->var;
}
//returns 1 if the variable is instantiated, 0 otherwise
//a variable is instantiated either by decision or implication (by unit resolution)
BOOLEAN sat_instantiated_var(const Var* var) {
ASSERT_TEST(!sat_implied_literal(var->pos)||!sat_implied_literal(var->neg)) //pos, neg should not be all implied
return (sat_implied_literal(var->pos)||sat_implied_literal(var->neg));
}
//returns 1 if all the clauses mentioning the variable are subsumed, 0 otherwise
BOOLEAN sat_irrelevant_var(const Var* var) {
c2dSize i;
Clause* clause;
for (i=0; i<sat_var_occurences(var); i++) {
clause = sat_clause_of_var(i, var);
if (sat_subsumed_clause(clause))
continue;
else
return 0;
}
return 1;
//returns 1 if the variable is instantiated, 0 otherwise
//a variable is instantiated either by decision or implication (by unit resolution)
BOOLEAN sat_instantiated_var(const Var* var) {
Lit* plit = sat_pos_literal(var);
Lit* nlit = sat_neg_literal(var);
return sat_implied_literal(plit) || sat_implied_literal(nlit);
}
//returns 1 if the variable is instantiated, 0 otherwise
//a variable is instantiated either by decision or implication (by unit resolution)
BOOLEAN sat_instantiated_var(const Var* var) {
return sat_implied_literal(var->p_literal) | sat_implied_literal(var->n_literal);
}
