I don´t understand how this word (build from a standard model) can be transformed in this way:
$$abca^{-1}b^{-1}c^{-1} = aba^{-1}b^{-1}cc^{-1}$$
For completeness I put the next (it is trivial): $$aba^{-1}b^{-1}cc^{-1} = T \# cc^{-1} = T \# S^2 = T$$
Thank you all.
Excuse me, YAlexandrov, but following your instruction (I suppose in the same sense) I obtain:
And still I don´t see how you get $T \# S^2$.
Thank you very much!