The Vickrey-Clarke-Groves (VCG) mechanism is infamously revenue non-monotone in combinatorial auctions. I.e., when a buyer increases their value for a bundle of items, the total auction revenue may decrease. Combinatorial auctions exhibit complementarities which broadly result in complexities in auction theory. This brief note shows that non-monotonicity in multi-item auctions is not a result of complementarities, and in fact, VCG is revenue non-monotone even in matching markets.

翻译：Vickrey-Clarke-Groves (VCG) 机制在组合拍卖中因其收入非单调性而广为人知。即当买家提高其对某物品组合的估值时，拍卖总收入反而可能下降。组合拍卖表现出互补性，这通常会导致拍卖理论的复杂性。本简报指出，多物品拍卖中的非单调性并非源于互补性；事实上，即使在匹配市场中，VCG 机制也表现出收入非单调性。