ex metric; /**< Metric of the space, all constructors make it an indexed object */
int commutator_sign; /**< It is the sign in the definition e~i e~j +/- e~j e~i = B(i, j) + B(j, i)*/
};
ex metric; /**< Metric of the space, all constructors make it an indexed object */
int commutator_sign; /**< It is the sign in the definition e~i e~j +/- e~j e~i = B(i, j) + B(j, i)*/
};