-/** 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);
-