How are value chains different from the commoditysystem?
价值链与商品系统有什么不同？
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This article introduces a concept of value function, which is a mapping from a commoditysystem, which has no comparability, to a comparable value system.
本文首先提出了价值函数的概念，它是把不具有直接可比性的商品投影到某个具有可比性的价值系统的影射。
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In the grass-fed system, farmers are also not subject to the wildly fluctuating milk prices of the international commodity market.