• Corpus ID: 119720876

An invariant detecting rational singularities via the log canonical threshold

@article{Cluckers2019AnID,
  title={An invariant detecting rational singularities via the log canonical threshold},
  author={Raf Cluckers and Mircea Mustaţǎ},
  journal={arXiv: Algebraic Geometry},
  year={2019}
}

• R. Cluckers, M. Mustaţǎ
• Published 23 January 2019
• Mathematics
• arXiv: Algebraic Geometry

We show that if f is a nonzero, noninvertible function on a smooth complex variety X and J_f is the Jacobian ideal of f, then lct(f, J_f^2)>1 if and only if the hypersurface defined by f has rational singularities. Moreover, if this is not the case, then lct(f, J_f^2)=lct(f). We give two proofs, one relying on arc spaces and one that shows that the minimal exponent of f is at least as large as lct(f, J_f^2). In the case of a polynomial over the algebraic closure of Q, we also prove an analogue of this latter inequality, with the minimal exponent replaced by the motivic oscillation index moi(f).