Which conditions are necessary to explain that the upper and lower integrals of a bounded function exist?
1
a, b ϵ R, a < b, and f ∶ [a, b] → R
2
a, b ϵ R, a < b, and f ∶ [a, b] → R be bounded
3
a, b ϵ R, a < b, and f ∶ [a, b] → Z be bounded
4
a, b ϵ R, a > b, and f ∶ [a, b] → R