An action of a complex reductive group $\mathrm G$ on a smooth projective variety $X$ is regular when all regular unipotent elements in $\mathrm G$ act with finitely many fixed points. Then the complex $\mathrm G$-equivariant cohomology ring of $X$ is isomorphic to the coordinate ring of a certain regular fixed point scheme. Examples include partial flag varieties, smooth Schubert varieties and Bott-Samelson varieties. We also show that a more general version of the fixed point scheme allows a generalisation to GKM spaces, such as toric varieties.

Comment: 57 pages, 7 figures. Comments are welcome

• 14F43 - Other algebro-geometric (co)homologies (e.g., intersection, equivariant, Lawson, Deligne (co)homologies)
• 14L30 - Group actions on varieties or schemes (quotients)
• 14M25 - Toric varieties, Newton polyhedra, Okounkov bodies
• 55N91 - Equivariant homology and cohomology in algebraic topology