def solveone(colnum, filename):
graph = dimacs.loadGraph("all-instaces/" + filename)
edgelist = dimacs.edgeList(graph)
sat = graphcoloringtosat(graph, colnum)
# print(sat)
sol = pycosat.solve(sat)
# print("\n", sol)
if sol != u'UNSAT':
print(checkcolouring(sol, edgelist, colnum))
def remove_edges(graph, u, v):
for neigh_u in graph[u].copy():
graph[u].remove(neigh_u)
graph[neigh_u].remove(u)
for neigh_v in graph[v].copy():
graph[v]. remove(neigh_v)
graph[neigh_v].remove(v)
return dim.edgeList(graph)
def find_coverage(graph, vertices, valid_graph):
graph_list = dim.edgeList(graph)
solution = set()
while len(solution) < vertices - 1 and graph_list:
u, v = graph_list.pop()
graph_list = remove_edges(graph, u, v)
solution.add(u)
solution.add(v)
if solution is not None and dim.isVC(valid_graph, solution):
return solution
def graphcoloringtosat(graph, k):
edgeList = dimacs.edgeList(graph)
satclause = []
vertexclauses = []
for i, j in edgeList:
if i not in vertexclauses:
satclause += preparevertexclause(i, k)
vertexclauses += [i]
if j not in vertexclauses:
satclause += preparevertexclause(j, k)
vertexclauses += [j]
satclause += prepareedgeclause(i, j, k)
return satclause
def coverage_2approx(name):
# load graph
path = 'graph\\' + name
graph = dim.loadGraph(path)
solution_path = path + '.sol'
# find coverage
graph_list = dim.edgeList(graph)
vertices = len(graph)
graph_copy = copy.deepcopy(graph)
solution = find_coverage(graph_copy, vertices, graph_list)
dim.saveSolution(solution_path, solution)
print('Solution for: ' + name + ' saved')
def solveall():
directory = os.fsencode("all-instaces")
for file in os.listdir(directory):
filename = os.fsdecode(file)
if filename.endswith(".col"):
print(filename)
graph = dimacs.loadGraph("all-instaces/" + filename)
edgelist = dimacs.edgeList(graph)
g = copy.deepcopy(graph)
k = 2
sol = pycosat.solve(graphcoloringtosat(g, k))
while sol == u'UNSAT' and k < 1000:
print(k)
k += 1
g = copy.deepcopy(graph)
sol = pycosat.solve(graphcoloringtosat(g, k))
print(filename, k, checkcolouring(sol, edgelist, k))
def check_coverage(name):
path = 'graph\\' + name
solution_filename = 'graph\\' + name + '.sol'
graph = dim.loadGraph(path)
graph_list = dim.edgeList(graph)
vertices = len(graph)
solution = set()
size = 0
for k in range(1, vertices):
if not graph[k]:
solution.add(k)
size += 1
solution_copy = copy(solution)
for k in range(size, vertices):
solution = find_coverage(graph_list, solution_copy, k)
if solution is not None and dim.isVC(graph_list, solution):
dim.saveSolution(solution_filename, solution)
break