Systematic Detection of Exception Occurrences

In proving the correctness of a program, a common strategem is to consider only initial states in which certain properties are satisfied. For example, in the knowledge that a given array contains at least one positive element, one might prove a program for finding, say, the first positive element in that array, even though the program may otherwise (i.e. if the array does not contain any positive elements) lead to unpredictable results.