电大西方经济学业--完全竞争和完全垄断条件下厂商均...小抄参考.doc

专业好文档完全竞争和完全垄断条件下厂商均衡的比较一、完全竞争、完全垄断、垄断竞争及寡头垄断的含义及其形成条件1. 完全竞争的含义：完全竞争是指竞争不受任何阻碍和干扰的市场结构。 主要条件：（1）市场上有无数个购买者和生产者。（2）市场上的产品是无差异的。（3）厂商和生产要素可以自由进退和自由流动。（4）购买者和生产者对市场信息完全了解。 由此可见，完全竞争市场是一个理想化的模型，但一般认为，在完全竞争市场中资源配置最为合理，资源利用最为充分，生产效率最高，可以作为衡量其他现实市场的一个标准。同时，完全竞争市场理论是其他各种市场理论的基础。2完全垄断的含义：完全垄断是指整个行业中只有一个厂商的市场结构。 主要条件：（1）厂商即行业，即整个行业中只有一个厂商，它提供了整个行业所需要的全部产量。（2）厂商所生产的产品有极大特殊性，且没有任何替代品，即产品的需求交叉弹性为0，  即EAB=0。这样，厂商就不受任何竞争者的威胁。（3）其他厂商几乎不可能进入该行业。 在这些假设条件下，一个完全垄断者就没有了竞争对手，市场中完全没有竞争的因素存在，厂商可以控制和操纵市场价格。3.  垄断竞争的含义：垄断竞争是指许多厂商生产和销售有差别的同类产品，市场中既有竞争因素又有垄断因素存在的市场结构。 主要条件：（1）市场上有很多的生产者和购买者，每一个生产厂商的生产规模都比较小。（2）行业中厂商生产的产品是有差别的，而这些产品彼此之间又存在某种替代性。（3）进入市场的障碍较少，生产厂商和生产要素都可以比较自由地进出市场。 比较垄断竞争市场和完全竞争市场的条件，我们可以发现它们的根本区别在于产品的差别性：完全竞争市场中各厂商所生产的产品是无差别的，而在垄断竞争市场中各厂商提供的是有差别的产品。4.  寡头垄断的含义：寡头垄断是指少数几个厂商控制整个市场的生产和销售的市场结构。 主要条件：（1）行业中厂商数量较少。寡头垄断市场上，厂商的数量较少，因而每一个厂商在市场中都有相当大的份额，当它改变自己的产量和价格时，会对市场的均衡价格和销售量产生影响，并且会影响竞争对手的利润。（2）厂商所生产的产品可以无差别，也可以有差别，前者如钢铁、制铝等行业，被称为纯粹寡头；后者如汽车、家电等行业，被称为差别寡头。（3）进入寡头垄断市场存在比较大的障碍，这种障碍表现在现有厂商比试图进入该市场的厂商在规模经济、技术装备、获得政府特许、对投入要素的控制等方面中的任何一方面都占据有优势。         二需求曲线和收益曲线1完全竞争条件下的需求曲线和收益曲线：在完全竞争市场中，厂商是市场价格的接受者，每一个厂商都可以按照一个既定的价格售出其原意提供的商品数量，因此，单个厂商在市场中面对的是一条具有完全弹性的、水平的需求曲线。2完全垄断厂商的需求曲线和收益曲线：在完全垄断市场上，由于市场中只有一家厂商，对垄断者产品的需求，就是对整个市场产品的需求，所以，垄断者所面临的需求曲线就是整个市场的需求曲线。3垄断竞争厂商的需求曲线：垄断竞争市场上的厂商面对的需求曲线既不像完全竞争市场上的厂商面对的需求曲线那样水平，也不像在完全垄断市场上的厂商面对的需求曲线那样陡峭，而是比较平坦的向右下方倾斜的曲线。三厂商短期均衡和长期均衡1厂商短期均衡：在短期内，完全竞争市场上的产品价格和生产规模是确定的，厂商只能在既定的生产规模下通过调整产量来实现利润最大化，并且各厂商由于短期内生产技术相对稳定，其成本结构也不易变化。 完全竞争市场上，厂商短期均衡的条件是：边际收益等于短期边际成本。 若价格大于短期平均成本，厂商可获得超额利润；若价格小于短期平均成本，厂商就有亏损；若价格等于短期平均成本，厂商无超额利润，但有正常利润。 亏损状态下，厂商继续生产的条件是：价格大于或者等于短期平均可变成本，这时厂商就能收回全部可变成本。2. 厂商长期均衡：在短期内，完全竞争厂商虽然可以实现均衡，但由于不能调整生产规模，在短期均衡时可能会亏损，或者有超额利润。但在长期中，所有生产要素的数量都是可变的，厂商就可以通过调整自身的规模或改变行业中厂商的数量来消除亏损，或者瓜分超额利润，最后超额利润为0，实现新的均衡，即长期均衡。四供给曲线 在完全垄断条件下，由于价格不是固定的，而要通过产量和价格调整来实现MR=SMC的原则，并且P（AR,，d）MR，所以，随着向右下方倾斜的需求曲线位移，价格和产量之间不存在那种一一对应的关系，因此不存在有规律性的供给曲线。Winger Tuivasa-Sheck, who scored two tries in the Kiwis' 20-18 semi-final win over England, has been passed fit after a lower-leg injury, while Slater has been named at full-back but is still recovering from a knee injury aggravated against USA.Both sides boast 100% records heading into the encounter but Australia have not conceded a try since Josh Charnley's effort in their first pool match against England on the opening day.Aussie winger Jarryd Hayne is the competition's top try scorer with nine, closely followed by Tuivasa-Sheck with eight.But it is recently named Rugby League International Federation player of the year Sonny Bill Williams who has attracted the most interest in the tournament so far.The Kiwi - with a tournament high 17 offloads - has the chance of becoming the first player to win the World Cup in both rugby league and rugby union after triumphing with the All Blacks in 2011."I'd give every award back in a heartbeat just to get across the line this weekend," said Williams.The (lack of) air up there Watch mCayman Islands-based Webb, the head of Fifa's anti-racism taskforce, is in London for the Football Association's 150th anniversary celebrations and will attend City's Premier League match at Chelsea on Sunday."I am going to be at the match tomorrow and I have asked to meet Yaya Toure," he told BBC Sport."For me it's about how he felt and I would like to speak to him first to find out what his experience was."Uefa has opened disciplinary proceedings against CSKA for the "racist behaviour of their fans" during City's 2-1 win.Michel Platini, president of European football's governing body, has also ordered an immediate investigation into the referee's actions.CSKA said they were "surprised and disappointed" by Toure's complaint. In a statement the Russian side added: "We found no racist insults from fans of CSKA." Baumgartner the disappointing news: Mission aborted.The supersonic descent could happen as early as Sunda.The weather plays an important role in this mission. Starting at the ground, conditions have to be very calm - winds less than 2 mph, with no precipitation or humidity and limited cloud cover. The balloon, with capsule attached, will move through the lower level of the atmosphere (the troposphere) where our day-to-day weather lives. It will climb higher than the tip of Mount Everest (5.5 miles/8.85 kilometers), drifting even higher than the cruising altitude of commercial airliners (5.6 miles/9.17 kilometers) and into the stratosphere. As he crosses the boundary layer (called the tropopause),e can expect a lot of turbulence.The balloon will slowly drift to the edge of space at 120,000 feet ( Then, I would assume, he will slowly step out onto something resembling an Olympic diving platform.They blew it in 2008 when they got caught cold in the final and they will not make the same mistake against the Kiwis in Manchester.Five years ago they cruised through to the final and so far history has repeated itself here - the last try they conceded was scored by England's Josh Charnley in the opening game of the tournament.That could be classed as a weakness, a team under-cooked - but I have been impressed by the Kangaroos' focus in their games since then.They have been concentrating on the sort of stuff that wins you tough, even contests - strong defence, especially on their own goal-line, completing sets and a good kick-chase. They've been great at all the unglamorous stuff that often goes unnoticed in the stands but not by your team-mates.It is as though their entire tournament has been preparation for the final.In Johnathan Thurston, Cooper Cronk, Cameron Smith and either Billy Slater or Greg Inglis at full-back they have a spine that is unmatched in rugby league. They have played in so many high-pressure games - a priceless asset going into Saturday.The Kiwis are a lot less experienced but winning a dramatic match like their semi-final against England will do wonders for their confidence.They defeated Australia in the Four Nations final in 2010 and the last World Cup, and know they can rise to the big occasion.