Using TraceDummy

[Partha Mukhopadhyay]

Hello,

I'm very new to using xAct and I'm here to get some help. 

(1) I would like to split contracted indices into those belonging to two different subspaces. The parent indices, say $\mu, \mu1, \cdots$ and both the subspace indices, say $\alpha, \alpha1, \cdots$ and $s, s1, \cdots$ are all defined. I understand that I should use TraceDummy for this purpose. However, I don't care what particular parent (contracted) index is split into what symbols belonging to subspace indices. All that I care is that all such contracted indices be split properly. How to do this in a simple manner? I guess something like input 7 in the following link

http://www.xact.es/Documentation/HTML/HTMLLinks/xTensor/HTMLLinks/TraceDummy.nb_1.html

can be used. But I'm not understanding this command and the result at all. 

(2) How do I proceed when the second subspace is one dimensional and I want use only one symbol, say $s$ (or any number, say $5$)? TraceDummy, of course, finds it erroneous if the indices are repeated (without being properly contracted). 

Sorry for my lack of familiarity of the subject and thanks a lot in advance.

-Partha