code: private String getHalfMatrixString(Permutation permutation) {
          StringBuilder builder = new StringBuilder(permutation.size());
          int size = permutation.size();
          for (int indexI = 0; indexI < size - 1; indexI++) {
              for (int indexJ = indexI + 1; indexJ < size; indexJ++) {
                  builder.append(getConnectivity(permutation.get(indexI), permutation.get(indexJ)));
              }
          }
          return builder.toString();
      }
docs: Get the upper-half of the adjacency matrix under the permutation.
  
  @param permutation a permutation of the adjacency matrix
  @return a string containing the permuted values of half the matrix