Given acceptance regions A := A g 1 (γ 1 ) and B := A g 2 (γ 2 ), both SF make the same decision for any candidates in the intersection A ∩ B (both SF accept) and in the "complement" Ω \ (A ∪ B) (both SF reject).
the performance of g 1 and g 2 can only differ in the regions D 1 := A \ B (g 1 accepts, but g 2 rejects) and B \ A (vice versa).