Example: The set of all integers, Z Then3∈Z,-8∈Z,6.5gZ These sets, each denoted using a boldface letter, play an important role in discrete mathematics: N=0, 1, 2,, the set of natural number FF(,2, -1, 0, 1, 2 ., the set of integers F=Z=1, 2, ., the set of positive integers Z=1, -2,, the set of negative integers Q={p/qlp∈Z2q∈Z,q≠0}, the set of rational numbers Q, the set of positive rational numbers Q, the set of negative rational numbersExample:The set of all integers, Z. Then 3Z, -8Z, 6.5Z These sets, each denoted using a boldface letter, play an important role in discrete mathematics: N={0,1,2,…}, the set of natural number I=Z={…,-2,-1,0,1,2,…}, the set of integers I +=Z+={1,2,…}, the set of positive integers I -=Z-={-1,-2,…}, the set of negative integers Q={p/q|pZ,qZ,q0}, the set of rational numbers Q+ , the set of positive rational numbers Q- , the set of negative rational numbers