A set may be given a name or symbol. Italicized upper case letters (e.g. A, B, X, Y) are often used to represent sets. Double-struck upper case letters represent particular sets. Z represents the set of all integers. Z= {i :i is an integer } = { ..., -2,-1,0, 1, 2, ... } z* represents the set of all positive integers. z* = {i: ie Z, >0} = { 1, 2, 3, ... } Z Z represents the set of all negative integers. = {i: ie Z, i0} = { 1, 2, 3, ... } Z Z represents the set of all negative integers. = {i: ie Z, i