Question: Collecting coeffients in a huge sum

Note added: Issue resolved, see my comment below.

I have a sum of several thousands addends each of which is the product of a c-number times a product of 6 Grassmann-odd degrees of freedom, the latter of which does each belong to a set of 24 Grassmannians. The specific numbers are not that important, though.

This sum should equal zero. So I would like to add all c-numbers multiplying the same product of six Grassmannians, taking proper care of anticommutativity, of course. The sum would then be zero if all these sums of c-numbers are zero. Unfortunately, using Physics:-Coefficients is far too slow; actually, it has never succeeded in even completing the calculation.

Therefore, I have tried to loop through all the addends, splitting each one of them using selectremove(), and then adding the c-numbers in an Array (properly indexed), or in a table (associatively indexed, of course). Consistently, by converting the Array and table to two sets, the two methods result in the same set of equations. But solving these equations yields a result that is not stable: it varies from session to session.

I am baffled. Can anyone give me a hint to a safe and reasonably quick method for extracting these c-number-valued equations?, for there has to be something wrong with what I do.

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