The product rule in \(\kappa ^*({\mathcal {M}}_{g,n}^{ct})\) (Q1741832)

The paper under review concerns the kappa ring of the moduli spaces of curves of compact type. The main result is an explicit formula expressing product of kappa classes in terms of the additive basis introduced in [\textit{R. Pandharipande}, Acta Math. 208, No. 2, 335--388 (2012; Zbl 1273.14057)]. To establish the formula, the author reduces the computation to the genus zero case by a result in [loc. cit.], then genus zero computations can be handled using results in [\textit{S. Keel}, Trans. Am. Math. Soc. 330, No. 2, 545--574 (1992; Zbl 0768.14002)].