Adams operations on the virtual K-theory of P(1, n)

摘要

We analyze the structure of the virtual (orbifold) K-theory ring of the complex orbifold P(1, n) and its virtual Adams (or power) operations, by using the non-Abelian localization theorem of Edidin-Graham D. Edidin and W. Graham, Nonabelian localization in equivariant K-theory and Riemann-Roch for quotients, Adv. Math. 198(2) (2005) 547-582. In particular, we identify the group of virtual line elements and obtain a natural presentation for the virtual K-theory ring in terms of these virtual line elements. This yields a surjective homomorphism from the virtual K-theory ring of P(1, n) to the ordinary K-theory ring of a crepant resolution of the cotangent bundle of P(1, n) which respects the Adams operations. Furthermore, there is a natural subring of the virtual K-theory ring of P(1, n) which is isomorphic to the ordinary K-theory ring of the resolution. This generalizes the results of Edidin-Jarvis-Kimura D. Edidin, T. J. Jarvis and T. Kimura, Chern classes and compatible power operation in inertial K-theory, Ann. K-Theory (2016), who proved the latter for n = 2, 3.