Subsection 3.2.1 Dummy Suffix
If suffix \(i\) occurs twice in a term, then that suffix \(i\) is called dummy suffix. For example, \(i\) is a dummy suffix in \(a_{ij}x_{i}\text{.}\) Also a dummy suffix can be replace by another dummy suffix i.e., \(a_{ij}x_{i}\equiv a_{kj}x_{k}\text{.}\)
