-9 < x< 9 ⇒ x∈ {-8,-7,-6,-5,-4,-3,-2,-1,0,1,2,3,4,5,6,7,8}
A= {-8,-7,-6,-5,-4,-3,-2,-1,0,1,2,3,4,5,6,7,8}
B= {-4,-3,-2,-1,0,1,2,3,4,5,6,7,8}
AUB= {-8,-7,-6,-5,-4,-3,-2,-1,0,1,2,3,4,5,6,7,8}
A intersectat B={-4,-3,-2,-1,0,1,2,3,4,5,6,7,8}
A-B= {-8,-7,-6,-5}
B-A=Ф multimea vida