3.1 Lists

Counting

Lists

• a list is an ordered sequence of objects
• Denoted using parentheses (a1, a2, …, an)
  • E.g. $(a,b,c,d,e)\ne (b,a,c,d,e)$
  • Duplicates are allowed
• Two lists are equal if they have exactly the same entries in exactly the same positions.

Empty List

• the empty list is denoted using ()

String

• A list of symbols written without parentheses and commas is called a string.
  • E.g. HHTHTTTHHT