Donaldson theory studies smooth oriented 4-manifolds using moduli spaces of anti-self-dual connections on principal bundles. Intersections in these moduli spaces define the Donaldson invariants, which distinguish smooth structures that are invisible to ordinary topological invariants.
Donaldson Theory
See also
Donaldson Invariants, Moduli SpaceExplore with Wolfram|Alpha
References
Donaldson, S. K. "An Application of Gauge Theory to Four-Dimensional Topology." J. Differential Geom. 18, 279-315, 1983. https://doi.org/10.4310/jdg/1214437665.Cite this as:
Weisstein, Eric W. "Donaldson Theory." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/DonaldsonTheory.html