When the left and right delimiter are the same symbol
From Why start at x, y, z
When the left and right delimiter are the same symbol, for example a vertical line, there can be more than one way of interpreting an expression with several sets of that delimiter.
For example, when a vertical line is used to represent the absolute value (or modulus) of a number, the following expression has at least two plausible interpretations, because Juxtaposition means combine in the obvious way
\[ |x|y|z| \]
If we write "the absolute value of $x$" as "$\operatorname{abs}(x)$", then the expression above could be interpreted as:
- \(\operatorname{abs}(x) \cdot y \cdot \operatorname{abs}(z)\)
- \(\operatorname{abs}(x \cdot \operatorname{abs}(y) \cdot z)\)
