Because it implies a type of curve is not “well-behaved,” a result named for Sonnenschein and Mantel suggests that this concept may not be predictably unique. An “approximate” form of this concept can be bound to “convexified” economies in an application of the Shapley–Folkman lemma. Prices are adjusted in a process that explains this concept called tâtonnement (“tah-tun-MAWN”). Using Kakutani’s fixed point theorem, Walrasian theorist Lionel W. McKenzie provided proof for a “general” form of this concept (-5[1])extended by Kenneth Arrow and Gérard Debreu. When this concept is not achieved, economic efficiency decreases, forming a deadweight loss. For 10 points, supply and demand curves meet (10[1])at a point named after what concept to achieve (-5[1])balance? ■END■ (10[2])