One-Form
TOPICS
A linear real-valued function 
of vectors 
such that 
. Vectors (i.e.,
contravariant vectors or "kets"
) and one-forms (i.e., covariant
vectors or "bras" 
) are dual to each other.
Therefore
The operation of applying the one-form to a vector 
is called tensor
contraction.
See also
Angle Bracket, Bra, Comma Derivative, Contravariant Vector, Covariant Vector, Differential k-Form, Ket, Vector
Explore with Wolfram|Alpha
More things to try:
Cite this as:
Weisstein, Eric W. "One-Form." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/One-Form.html