Kronecker Delta - Generalizations of The Kronecker Delta

Generalizations of The Kronecker Delta

Tensors
Glossary of tensor theory
Scope Mathematics
  • Coordinate system
  • Multilinear algebra
  • Euclidean geometry
  • Differential geometry
  • Exterior calculus

Physics and engineering

  • Continuum mechanics
  • Electromagnetism
  • Transport phenomena
  • General relativity
  • Computer vision
Notation
  • Index notation
  • Multi-index notation
  • Einstein notation
  • Ricci calculus
  • Penrose graphical notation
  • Voigt notation
  • Abstract index notation
Tensor definitions
  • Tensor (intrinsic definition)
  • Tensor field
  • Tensor density
  • Tensors in curvilinear coordinates
  • Mixed tensor
  • Antisymmetric tensor
  • Symmetric tensor
Operations
  • Tensor product
  • Wedge product
  • Tensor contraction
  • Transpose (2nd-order tensors)
  • Raising and lowering indices
  • Hodge dual
  • Covariant derivative
  • Exterior derivative
  • Exterior covariant derivative
  • Lie derivative
Related abstractions
  • Dimension
  • Vector, Vector space
  • Multivector
  • Covariance and contravariance of vectors
  • Linear transformation
  • Matrix
  • Differential form
  • Exterior form
  • Connection form
  • Spinor
  • Geodesic
  • Manifold
  • Fibre bundle
Notable tensors Mathematics
  • Kronecker delta
  • Levi-Civita symbol
  • Metric tensor
  • Christoffel symbols
  • Ricci curvature
  • Riemann curvature tensor
  • Weyl tensor

Physics

  • Stress tensor
  • Stress–energy tensor
  • EM tensor
  • Einstein tensor
Mathematicians
  • Leonhard Euler
  • Carl Friedrich Gauss
  • Augustin-Louis Cauchy
  • Hermann Grassmann
  • Gregorio Ricci-Curbastro
  • Tullio Levi-Civita
  • Jan Arnoldus Schouten
  • Bernhard Riemann
  • Elwin Bruno Christoffel
  • Woldemar Voigt
  • Élie Cartan
  • Hermann Weyl
  • Albert Einstein

If it is considered as a type (1,1) tensor, the Kronecker tensor, it can be written with a covariant index j and contravariant index i:


\delta^{i}_{j} =
\begin{cases} 0 & (i \ne j), \\ 1 & (i = j).
\end{cases}

This (1,1) tensor represents:

  • The identity mapping (or identity matrix), considered as a linear mapping or
  • The trace or tensor contraction, considered as a mapping
  • The map, representing scalar multiplication as a sum of outer products.


The generalized Kronecker delta of order 2p is a type (p,p) tensor that is a completely antisymmetric in its p upper indices, and also in its p lower indices.

Read more about this topic:  Kronecker Delta