* @return newly constructed epsilon tensor */
ex lorentz_eps(const ex & i1, const ex & i2, const ex & i3, const ex & i4, bool pos_sig = false);
+/** Create an epsilon tensor in a 4-dimensional projection of a D-dimensional
+ * Minkowski space. It vanishes whenever one of the indices is not in the
+ * set {0, 1, 2, 3}.
+ *
+ * @param i1 First index
+ * @param i2 Second index
+ * @param i3 Third index
+ * @param i4 Fourth index
+ * @param pos_sig Whether the signature of the metric is positive
+ * @return newly constructed epsilon tensor */
+ex eps0123(const ex & i1, const ex & i2, const ex & i3, const ex & i4, bool pos_sig = false);
+
} // namespace GiNaC
#endif // ndef __GINAC_TENSOR_H__