a = b / 0; break; case 4: c = b - 4; a = b / c; break; }; } Symbolic Execution (Abstract interpretation) b: $b b: $b b: $b b: $b $b=[4,4] $b=[1,1] $b=[MIN,0],[2,3],[5,MAX] b: $b c: 0 $b=[4,4]; c=$b-4 c=0 b: $b c: 0 $b=[4,4] a=$b/$c case 4 c = b-4; switch(b) a = b/c; b: $b a = b/0;