One-dimensional Hurwitz spaces, modular curves, and real forms of Belyi meromorphic functions.
Let be an algebraic projective smooth and trigonal curve of genus . In this paper we define, in a way equivalent to that followed by A. Maroni in [1], an integer , called the species of , which is a birational invariant having the property that and mod(2). In section 1 we prove that for every and every , as before, there are trigonal curves of genus and species . In section 2 we define the space of moduli of trigonal curves of genus and species . We note that is irreducible...
We give a review of our construction of a cohomological field theory for quasi-homogeneous singularities and the -spin theory of Jarvis-Kimura-Vaintrob. We further prove that for a singularity of type our construction of the stack of -curves is canonically isomorphic to the stack of -spin curves described by Abramovich and Jarvis. We further prove that our theory satisfies all the Jarvis-Kimura-Vaintrob axioms for an -spin virtual class. Therefore, the Faber-Shadrin-Zvonkine proof of the...
If denotes the variety of irreducible plane curves of degree with exactly nodes as singularities, Diaz and Harris (1986) have conjectured that is a torsion group. In this note we study rational equivalence on some families of singular plane curves and we prove, in particular, that is a finite group, so that the conjecture holds for . Actually the order of is , the group being cyclic if is odd and the product of and a cyclic group of order if is even.