2 papers
math.AG2001
Constructions of nontautological classes on moduli spaces of curves
T. Graber, R. Pandharipande
We construct explicit examples of algebraic cycles in \bar M_g (for large g congruent to 2 mod 4) and in M_2,20 (no bar) which are not in the tautological ring. In an appendix we g…
math.AG1999
Stable maps and branch divisors
B. Fantechi, R. Pandharipande
We construct a natural branch divisor for equidimensional projective morphisms where the domain has lci singularities and the target is nonsingular. The method involves generalizin…