In mathematics, a Hartshorne ellipse is an
ellipse in the
unit ball
Unit may refer to:
Arts and entertainment
* UNIT, a fictional military organization in the science fiction television series ''Doctor Who''
* Unit of action, a discrete piece of action (or beat) in a theatrical presentation
Music
* ''Unit'' (a ...
bounded by the
4-sphere
In mathematics, an -sphere or a hypersphere is a topological space that is homeomorphic to a ''standard'' -''sphere'', which is the set of points in -dimensional Euclidean space that are situated at a constant distance from a fixed point, call ...
S
4 such that the ellipse and the circle given by intersection of its plane with S
4 satisfy the
Poncelet condition that there is a triangle with vertices on the circle and edges tangent to the ellipse. They were introduced by , who showed that they correspond to ''k'' = 2
instantons
An instanton (or pseudoparticle) is a notion appearing in theoretical and mathematical physics. An instanton is a classical solution to equations of motion with a finite, non-zero action, either in quantum mechanics or in quantum field theory. Mo ...
on S
4.
References
*
Algebraic geometry
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