Cotangent Bundle
The cotangent bundle of a manifold is similar to the tangent bundle, except that it is the set (x,f) where x in M and f is a dual vector in the tangent space to x in M. The cotangent bundle is denoted T^*M.
See also
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Cite this as:
Weisstein, Eric W. "Cotangent Bundle." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/CotangentBundle.html