We study sealed-bid first-price auction for one commodity. While traditional model (Vickrey, 1961) consists of only one stage of bidding, we introduce a new model by adding a new stage of application before the stage of final bidding. In the application stage, each bidder submits a tentative sealed bid, and it is then announced who is the tentative winner. Then in the bidding stage, each bidder gives his final (sealed) bid, and the final winner receives the commodity by paying his final bid. / To analyze the model, we use the equilibrium concepts of Weak Perfect Bayesian Equilibrium (WPBE). The role of the tentative bid can be regarded as a pre-play communication between the bidders. We obtain three main results: / 1) Our Theorem 1 shows that every equilibrium in the traditional one-stage model can be realized as a WPBE in our two-stage model, and the tentative bids of bidders are independent of their private values. / 2) Our Theorem 2 shows that if one requires the tentative bids of bidders to be strictly increasing with their private values, then no symmetric WPBE exists. / 3) Our Theorem 3 shows that if each bidder uses a weakly increasing step function as the tentative bidding strategy, then no symmetric WPBE exists. / Our work suggests that if each bidder is free to change his final bid from the tentative bid, then introducing the application system does not affect the outcome of the auction. / 本文章主要論及首價密封投標拍賣。傳統的拍賣只有一個階段﹐而在這篇文章我們會在傳統拍賣前加一個「申請階段」。在「申請階段」中﹐每名投標者需要遞交一個意向價格﹐拍賣者再根據意向價格宣佈那位投標者成為申請人。之後的拍賣中﹐每名投標者會遞交一個最終價格﹐最高價者會成功投得該項商品。 我們會使用「弱完美貝葉斯均衡」(WPBE)的概念去分析本文中的模型。我們得到以下的三個主要結果: / 1)在定理一中﹐我們發現所有傳統單一階段拍賣中的均衡點, 在我們新申請拍賣的模型中﹐都會是弱完美貝葉斯均衡(WPBE)﹐而且投標者的意向價格會和他們對商品的自身價值沒有關係。 / 2)在定理二中﹐如果投標者的意向價格函數和對商品的自身價值是嚴格遞升﹐那麼對稱性弱完美貝葉斯均衡不會存在。 / 3)在定理三中﹐如果申請階段的策略是遞升階梯函數﹐那麼對稱性弱完美貝葉斯均衡不會存在。 / 我們的研究指出, 當投標者可以不受意向價格規範而自己更改最終價格﹐那麼加入「申請階段」也不會改變拍賣的結果。 / Ho, Man Kit. / Thesis M.Phil. Chinese University of Hong Kong 2014. / Includes bibliographical references (leave 41). / Abstracts also in Chinese. / Title from PDF title page (viewed on 18, October, 2016). / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only.