Dummy and Free Indices

[ehki...@gmail.com]

I need help with extracting all free and dummy indices from an expression. However, I encounter an issue where the dummy indices are being treated as free indices when I call them within a tensor. Does anyone know how to handle this properly?

I've attached a picture for reference.

Thank you in advance for your assistance!

Best regards,
Ehsan

[Thomas Bäckdahl]

Hi!

I think the problem here is that you are using
$PrePrint=ScreenDollarIndices;
This means that all indices with a $ symbol is replaced before it is displayed.
The actual expression in Out[361] should have the indices in Out[360]. However, before the expression is displayed they are changed to other indices not used in that expression.
You can use InputForm@% or FullForm@% to see what the expression actually is.

In your case I think you should do ScreenDollarIndices on expr before you extract the indices.

Regards
Thomas

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