# “a theory of generalized Donaldson-Thomas invariants” by Joyce & Song

Is anyone else working through this paper : http://arxiv.org/abs/0810.5645 ? I am trying to verifying example 6.2 (m=2 for simplicity) using only the definitions, namely:

J^{2\alpha}(\tau) = -1/4

(where \alpha satisfies M^{\alpha}_ss = M^{\alpha}_st and that Ext^1(E, E)=0 for any E \in M^{\alpha}_ss and finally that the only object of M^{m\alpha}_ss is E ^{\oplus m})

I keep getting -3/4. Has anyone else attempted to make such a computation? Did you get the answer you are supposed to get?

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Guided by the generous assistance of Dominic Joyce and Jonathan Wise, I have verified that J^{2\alpha}(\tau) = -1/4. I continue to work on proving the corresponding statement for a general m, using only the definitions. –  David Steinberg Nov 17 '09 at 2:39