“…as piece-wise approximations of the convex functions p z j (l) be the price at which a unit volume of electric energy is sold by the generator to utility company j, j ∈ 1, n, in the period of time from hour l −1 to hour l, l ∈ 1, 24, p u k (l) be the price at which a unit volume of electric energy is sold by the generator to group of advanced customers k, k ∈ 1, r in the period of time from hour l − 1 to hour l, l ∈ 1, 24, (24) be the vector whose component p u k (l) is the price at which a unit volume of electric energy is sold to group of advanced customers k by the generator in the period of time from hour l − 1 to hour l, k ∈ 1, r , l ∈ 1, 24.…”