“…If q I < q 0 and ρ(u, q I ) > g I and p I g I − f I ≤ p I ρ(u, q 0 ), for any user type φ = (u, v), ∀v < p I , it satisfies that y * (φ, θ I , q I ) = g I and y * (φ, θI , q I ) = ρ(u, q I ) by Equation ( 4). Thus we have that π y * (φ, θ I , q I ), v, θ I = vg I − f I ≤ p I g I − f I ≤ vρ(u, q 0 ) and π y * (φ, θI , q I ), v, θI = vρ(u, q I ) − f I − ρ(u, q I ) − g I p I ≤ vρ(u, q I ) − p I ρ(u, q I ) + p I ρ(u, q 0 ) ≤ vρ(u, q 0 ) by Equation (2). It implies that the user type φ = (u, v), ∀v < p I would not choose the ISP no matter it adopts the pricing strategy θ I or θI .…”