基于交易量的最优指令提交策略模型

构建了两个价位的指令驱动市场模型.交易者根据自己的估值选择提交限价指令或市价指令.假设交易量作为交易者的禀赋,可在一个连续区间上任意取值,从而提出限价收益曲线的概念,并结合该曲线给出基于交易量的最优指令提交策略时.最优指令提交策略不仅依赖于交易者的私人估值、市场深度和价差,同时依赖于交易者所持交易量.模型揭示以下几点微观特征:1.私人估值偏离证券基本价值较大的交易者倾向于提交市价订单,而私人估值接近证券基本价值的交易者倾向于提交限价订单;2.当市场深度较小时,交易者倾向于限价单;而市场深度较大时,交易者倾向于提交市价单;3.随价差的增加,交易者更倾向于提交限价订单.     

股票定向增发、盈余管理与公司的业绩滑坡——基于应计项目操控与真实活动操控方式下的研究

本文采用了应计项目操控与真实活动操控两种模型研究了我国上市公司定向增发新股过程中盈余管理行为以及之后的业绩表现,结果发现:中国上市公司在定向增发过程中会同时使用应计项目操控与真实活动操控两种盈余管理方式;进一步研究发现应计项目盈余管理会导致上市公司定向增发后业绩的短期滑坡,真实活动盈余管理会引起公司业绩的长期滑坡,真实活动盈余管理是上市公司定向增发之后业绩滑坡的主要原因。     

On the Existence of XOR-Based Codes for Private Information Retrieval with Private Side Information

We consider the problem of Private Information Retrieval with Private Side Information (PIR-PSI), wherein the privacy of the demand and the side information are jointly preserved. Although the capacity of the PIR-PSI setting is known, we observe that the underlying capacity-achieving code construction uses Maximum Distance Separable (MDS) codes therefore contributing to high computational complexity when retrieving the demand. Pointing at this drawback of MDS-based PIR-PSI codes, we propose XOR-based PIR-PSI codes for a simple yet non-trivial setting of two non-colluding databases and two side information files at the user. Although our codes offer substantial reduction in complexity when compared to MDS-based codes, the code-rate marginally falls short of the capacity of the PIR-PSI setting. Nevertheless, we show that our code-rate is strictly higher than that of XOR-based codes for PIR with no side information. As a result, our codes can be useful when privately downloading a file especially after having downloaded a few other messages privately from the same database at an earlier time-instant.