Duplicate values
•Array sum program:
i := 0; s := 0;
while i ¹ n do
  { s := s+b[i];  i := i+1 }
•b is unchanged inside loop
•Problem: at loop head
–88 £ b[n – 1] £ 99
–556 £ sum(b) £ 539
•Reason: more samples inside loop
These were eliminated from the procedure entry and exit, but remain at the loop head.

These values (–556, 539, –88, 99) happened to be the extrema -- the largest and smallest values seen on this particular set of runs of the program.