delta

• delta[a, -b] represents the identity tensor on any vector bundle.

• The tensors delta[a, -b] and delta[-b, a] are considered equivalent, and actually delta is defined as a symmetric tensor (though not orderless).
• The indices of delta are always staggered. When both indices have the same character then delta is inmediately converted into the (first) metric tensor of the vbundle of those indices.
• The indices of delta are always abstract. When one of the indices is a b-index or a c-index, then delta is inmediately converted into Basis, which is formally equivalent, but has Orderless attribute.
• See: Section 4.4
• See also: Gdelta.
• New in version 0.
• Last update: 15-X-2007 for version 0.9.3 of xTensor`.

Created by Mathematica  (May 16, 2008)