Tuple

A tuple is an ordered list of (not necessarily unique) elements.

• Notation: $(x_1,x_2,\dots ,x_n)$ for an $n$-tuple
• Order matters: $(a,b)\ne (b,a)$ in general
• Example: $(1,"x",\varnothing )$ is a 3-tuple

Properties:

• Tuples are distinct from sets because duplicates and order matter.
• A 1-tuple $(a)$ is sometimes just written as $a$