A conjectural formula for the double ramification cycle
-- Aaron Pixton, October 17, 2014

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Double ramification  cycles parametrize  curves that
admit maps  to the projective line  with specified ramification
profiles over  zero and infinity. These cycles  can be extended
to the moduli space of stable curves by using the virtual class
in relative Gromov-Witten theory. I will describe a conjectural
formula   for  these  extensions   in  terms   of  tautological
classes. The formula is  partially motivated by an analogy with
a recently proven formula for Witten's r-spin class.