This is a glossary of terms specific to differential geometry and differential topology. The following three glossaries are closely related:
Contents
See also:
Words in italics denote a self-reference to this glossary.
A
Atlas
B
Bundle, see fiber bundle.
C
Chart
Cobordism
Codimension. The codimension of a submanifold is the dimension of the ambient space minus the dimension of the submanifold.
Connected sum
Connection
Cotangent bundle, the vector bundle of cotangent spaces on a manifold.
Cotangent space
D
Diffeomorphism. Given two differentiable manifolds M and N, a bijective map
Doubling, given a manifold M with boundary, doubling is taking two copies of M and identifying their boundaries. As the result we get a manifold without boundary.
E
Embedding
F
Fiber. In a fiber bundle, π: E → B the preimage π−1(x) of a point x in the base B is called the fiber over x, often denoted Ex.
Fiber bundle
Frame. A frame at a point of a differentiable manifold M is a basis of the tangent space at the point.
Frame bundle, the principal bundle of frames on a smooth manifold.
Flow
G
Genus
H
Hypersurface. A hypersurface is a submanifold of codimension one.
I
Immersion
L
Lens space. A lens space is a quotient of the 3-sphere (or (2n + 1)-sphere) by a free isometric action of Zk.
M
Manifold. A topological manifold is a locally Euclidean Hausdorff space. (In Wikipedia, a manifold need not be paracompact or second-countable.) A Ck manifold is a differentiable manifold whose chart overlap functions are k times continuously differentiable. A C∞ or smooth manifold is a differentiable manifold whose chart overlap functions are infinitely continuously differentiable.
N
Neat submanifold. A submanifold whose boundary equals its intersection with the boundary of the manifold into which it is embedded.
P
Parallelizable. A smooth manifold is parallelizable if it admits a smooth global frame. This is equivalent to the tangent bundle being trivial.
Principal bundle. A principal bundle is a fiber bundle P → B together with an action on P by a Lie group G that preserves the fibers of P and acts simply transitively on those fibers.
Pullback
S
Section
Submanifold, the image of a smooth embedding of a manifold.
Submersion
Surface, a two-dimensional manifold or submanifold.
Systole, least length of a noncontractible loop.
T
Tangent bundle, the vector bundle of tangent spaces on a differentiable manifold.
Tangent field, a section of the tangent bundle. Also called a vector field.
Tangent space
Torus
Transversality. Two submanifolds M and N intersect transversally if at each point of intersection p their tangent spaces
Trivialization
V
Vector bundle, a fiber bundle whose fibers are vector spaces and whose transition functions are linear maps.
Vector field, a section of a vector bundle. More specifically, a vector field can mean a section of the tangent bundle.
W
Whitney sum. A Whitney sum is an analog of the direct product for vector bundles. Given two vector bundles α and β over the same base B their cartesian product is a vector bundle over B ×B. The diagonal map