Incorrect behaviour of meld?

Question

Hi! I'm trying to do some manipulations in supersymmetry. I'm getting this behaviour from the meld function:

{i, j, k,l,m,n}::Indices(position=fixed).
{i, j, k,l,m,n}::Integer(1..2).
{i, j, k,l,m,n}::AntiCommuting.

ex:=v^i v_i -v_i v^i;
meld(_);

This gives me an output of 0, but this should be $2v^iv_i$ in order to respect the anticommuting nature of the object.

One would also expect

ex:=v^i v_j -v_j v^i;
meld(_);

to give $2v^iv_j$, but rather it doesn't change the expression at all. Neither does canonicalise. I'd assume this is not the expected behaviour based on this question.

Let me know if this is not the case.

Answer 1

Hi @jjwoods.

The link provided in your question does not work properly, I suggest to edit the URL to raising-and-lowering-indices-with-an-anti-symmetric-tensor.

This issue might related to issue-in-sort_product-with-anticommuting-indices

Comments

Hi @doxdrum. I've fixed the link in my post. This is indeed related to the issue you linked, however it has no responses.

Answer 2

Meld does at present not work with anticommuting objects. Use canonicalise for now.