Please show a simple example showing difference b/w Indices(curved) and Indices(flat).

Question

We came across it in the Fierz Transformation tutorial. But did not understand the purpose of free and fixed indices.

Answer 1

Read the chapter on indices in the reference manual,

https://cadabra.science/notebooks/ref_indices.html

Hope that helps; if it doesn't, reply to this and I'll make another attempt.