我不确定，上节课prof刚刚讲的Ch还没仔细看书

我们讲的是由于税收引起的demand surplus 和 supply surplus 损失

deadweight loss

In terms of perfect competition, an individual firm as a price taker in the market, faces a constant demand curve and produces at price level where, MC=MR=P*. Therefore Social welfare(SW)=consumer surpls(CS)+Producer surpls(PS), the Parento Efficency is Achieved. (P*= the market equilibrium price, where Demand=Supply)

Assume that a perfect competition market has been monoplised over night. the monoplist faces a download slopping demand curve, which is the aggregate demand for the perfect competition market. so MR=<P*. In order to profit maximise, the monoplist will understandablely produce under condition of MC=MR, but in this case, demand>supply, P*<P^(Monolist's price). This causes deadweightloss(DWL), as Parento Effiecncy cannot be sustained, as monoply will never be allocatively efficent and very rarely be produvtively efficent. So SW=CS+PS+DWL

But this is not always the case, as the first degree of discrimination/price discriminiation is allowed, the SW will be sustained because the monoplist can charge different prices given every single unit of demands, i.e. SW=PS, where CS=0.

as an economist, we don't care who is benefited, as long as social welfare is sustained, we won't be worried

http://staff.bath.ac.uk/ecsjgs/Teaching/Industrial%20Organisation/Handouts/03%20-%20Homogenous%20Goods/Handout%203a.pdf

This is handouts from a lecuture, if you want read Page 3, which shows above arguments in terms of diagrams and maths formula, which may help to understand

deadweight loss?~

the deadweight loss?~ is paint to the thing like that :"sadjsdajkghk,bhio hap5n hastrhgj[sp jaskdugtjsla

sdhfgkjy jjgierhhasa hsaigh sdfgvg asjifgh8is jifgh0pwe sahdfioeww jsdaoiguj heifghaw8e sdfgewj "