SAT.c

// SAT.c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define MAX_CLAUSES 100
#define MAX_LITERALS 10

// SAT Instance structure to hold the CNF problem
typedef struct {
    int num_vars;
    int num_clauses;
    int clauses[MAX_CLAUSES][MAX_LITERALS];
} SAT_Instance;

// Function to parse CNF file
int parse_cnf_file(const char* filename, SAT_Instance* sat_instance) {
    FILE *file = fopen(filename, "r");
    if (!file) {
        perror("Error opening file");
        return -1;
    }

    char line[256];
    while (fgets(line, sizeof(line), file)) {
        if (line[0] == 'c') continue;  // Skip comments
        if (line[0] == 'p') {
            sscanf(line, "p cnf %d %d", &sat_instance->num_vars, &sat_instance->num_clauses);
        } else {
            static int clause_index = 0;
            int literal, literal_index = 0;
            char *token = strtok(line, " ");
            while (token != NULL && token[0] != '0') {
                literal = atoi(token);
                if (literal < -sat_instance->num_vars || literal > sat_instance->num_vars) {
                    fprintf(stderr, "Error: Invalid literal %d\n", literal);
                    fclose(file);
                    return -1;
                }
                sat_instance->clauses[clause_index][literal_index++] = literal;
                token = strtok(NULL, " ");
            }
            sat_instance->clauses[clause_index][literal_index] = 0;
            clause_index++;
        }
    }
    fclose(file);
    return 0;
}

// Print SAT instance for verification
void print_sat_instance(const SAT_Instance* sat_instance) {
    printf("SAT Instance with %d variables and %d clauses:\n", sat_instance->num_vars, sat_instance->num_clauses);
    for (int i = 0; i < sat_instance->num_clauses; i++) {
        printf("Clause %d: ", i + 1);
        for (int j = 0; sat_instance->clauses[i][j] != 0; j++) {
            printf("%d ", sat_instance->clauses[i][j]);
        }
        printf("\n");
    }
}

// Hypothetical SAT Solver function (Replace with actual PMLL solver)
int solve_sat_instance(SAT_Instance* sat_instance) {
    // This function should call the PMLL SAT solver function
    // Placeholder return value for demonstration
    printf("Solving SAT instance...\n");
    return 1;  // Assuming solution found
}

// PMLL SAT solver function
int pmll_sat_solver(SAT_Instance* sat_instance) {
    // TO DO: Implement the PMLL SAT solver algorithm
    // For now, just return a placeholder value
    return 1;
}

// Main function for SAT testing
int main() {
    SAT_Instance sat_instance;

    // Load and parse the SAT instance from a file
    if (parse_cnf_file("example.cnf", &sat_instance) != 0) {
        fprintf(stderr, "Failed to parse CNF file.\n");
        return 1;
    }

    // Print SAT instance to verify correctness
    print_sat_instance(&sat_instance);

    // Solve the SAT instance using the PMLL algorithm
    int result = pmll_sat_solver(&sat_instance);
    if (result) {
        printf("SAT instance is satisfiable.\n");
    } else {
        printf("SAT instance is unsatisfiable.\n");
    }

    return 0;
}