+/** Automorphism of the Clifford algebra, simply changes signs of all
+ * clifford units. */
+ex clifford_prime (const ex &e) ;
+
+/** Main anti-automorphism of the Clifford algebra: make reversion
+ * and changes signs of all clifford units*/
+inline ex clifford_bar(const ex &e) { return clifford_prime(e.conjugate());};
+
+/** Reversion of the Clifford algebra, coinsides with the conjugate() */
+inline ex clifford_star(const ex &e) { return e.conjugate();};
+
+ex delete_ONE (const ex &e);
+
+/** Calculation of the norm in the Clifford algebra */
+ex clifford_norm(const ex &e) ;
+
+/** Calculation of the inverse in the Clifford algebra */
+ex clifford_inverse(const ex &e) ;
+
+/** List or vector conversion into the Clifford vector
+ * @param v List or vector of coordinates
+ * @param mu Index (must be of class varidx or a derived class)
+ * @param metr Metric (must be of class tensor or a derived class)
+ * @param rl Representation label
+ * @return Clifford vector with given components */
+ex lst_to_clifford(const ex &v, const ex &mu, const ex &metr, unsigned char rl = 0) ;
+