def _adj(self, k):
        """
        Description:
            Adjacent breaking
        Paramters:
            k: not used
        """
        G = np.zeros((self.m, self.m))
        for i in range(self.m):
            for j in range(self.m):
                if i == j+1 or j == i+1:
                    G[i][j] =  1
        return G