It seems that my last email got chopped so I am resending it, sorry...

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Q4. "Indices" of various kinds proved to be useful in different areas of mathematics, e.g. linear algebra.

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Q5. I need expressions of the type \sum_{j=1}^n a_j b_j for an unspecified symbolic value n and quantities a_j and b_j *labelled* (rememberring that _indexed_ is already copyrighted) by j in this range.

I have the same type of concern.