From your description and sample solution, it is not at all clear what the function should return when the subtended set is not a range of contiguous integers. I.e., given your value of @F, what should range(1,8) return? (1,2,4,8) or (1,2,3,4,5,6,7,8) ?

Also, what guarantees will there be, regarding the orderedness and uniqueness of the elements of @F ?

jdporter
The 6th Rule of Perl Club is -- There is no Rule #6.