A seller charging competing buyers different prices for the same " commodity " or discriminating in the provision of " allowances " - - compensation for advertising and other services - - may be violating the robinson - patman act 一销售商就相同的商品向不同的竞买者索取不同的价格或在限量供应(如对广告或其它服务的补偿)中对购买者实行歧视的行为可能违反《鲁宾逊-帕特曼法》 。