Through function's differential, it finds the moral hazard between manufacturer and retailer, which proves the existence of Prisoners Dilemma it finds the supply chain.

然后通过支付函数的全微分，来揭示供应链中的道德风险问题，从而证明供应链内部存在囚徒困境现象。

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These include companies such as DHL, the high street chain Timpson and Amaryllis, which has used prisoners to help provide recycled furniture and fittings for the Olympic Games.

BBC: UK Politics