Riemannian manifolds category
Definition 0.1.
A category![]()
whose objects are all Riemannian manifolds
![]()
and whose morphisms are mappings between Riemannian manifolds is defined as the category of Riemannian manifolds.
0.1 Applications of Riemannian manifolds in mathematical physics
- 1.
The conformal Riemannian subcategory of , whose objects are Riemannian manifolds , and whose morphisms are conformal mappings

of Riemannian manifolds , is an important category for mathematical physics, in conformal theories.
- 2.
It can be shown that, if and are Riemannian manifolds, thena map is conformal (http://planetmath.org/ConformalMapping) iff for some scalar field (on ), where is the complex conjugate

of .
0.1.1 Category of pseudo-Riemannian manifolds
The category of pseudo-Riemannian manifolds (http://planetmath.org/PseudoRiemannianManifold) that generalize Minkowski spaces![]()
is similarly defined by replacing the Riemanian manifolds
![]()
in the above definition with pseudo-Riemannian manifolds
![]()
. Pseudo-Riemannian manifolds s were claimed to have applications in Einstein’s theory of general relativity (), whereas the subcategory
![]()
of four-dimensional Minkowski spaces in plays the central role in special relativity () theories.