The refelxity is a technical condition that ensures the existence of utility function. It is an axiom.

While local non-satiation is an assumption, which is one of the conditions of first and second welfare theorem.

And anothing needs to be pointed out here is that, local-nonsatiation does nor mean the more the better, it just means that in any neighbourhood of a consumption bundle, there is other consumption bundle which is prefered to the original one. While the more the better means monotonicity, which is stronger than local non-satiation.

非饱和性本身就是个假定，假定商品拥有得越多越好

反身性就是书上的解释，没必要深究

蓝色麻雀 发表于 2011-3-28 16:37 今天我也碰到了和楼主一样的问题，看了各位的讨论后我还是有点疑惑呀。。。反身性是指任何商品束至少和本身一样好。可是，这不是公理吗？难道还有自己比自己差或者自己比自己好啊？？还有既然都是公理了，还把它作为假定有何必要呢？还望各位能再指点指点。。。。谢谢！

蓝色麻雀 发表于 2011-3-28 16:37 今天我也碰到了和楼主一样的问题，看了各位的讨论后我还是有点疑惑呀。。。反身性是指任何商品束至少和本身一样好。可是，这不是公理吗？难道还有自己比自己差或者自己比自己好啊？？还有既然都是公理了，还把它作为假定有何必要呢？还望各位能再指点指点。

lifeilove 发表于 2005-8-19 23:24
其实就是定义在一个在一个集合上的偏好关系，一般的数学分析或实分析书中都会假定该集合的三个性质，这是其 ...