MASaraji

bin_matrix = [[0, 1, 0, 0,0], [1, 0, 1, 0,0], [0, 0, 0, 1,1], [0,0, 0, 0,0],[0,0,0,0,0]]
from itertools import product
a=product(range(len(bin_matrix)),repeat=3)
a=filter(lambda a:bin_matrix[a[0]][a[1]] and bin_matrix[a[1]][a[2]],a)

MASaraji

bin_matrix = [[0, 1, 0, 0], [1, 0, 1, 0], [0, 0, 0, 1], [0,0, 0, 0]]

length=range(len(bin_matrix))
for k in length:
    for i in length:
        for j in length:
            if bin_matrix[i][k] and bin_matrix[k][j]:
                bin_matrix[i][j] = 1