“Impossibility of speculation” theorems with noisy information
研究在信息系统中引入噪声后，投机不可能结果是否仍然成立。证明噪声趋近于零时模型收敛于无噪声的不可投机结果，但一定程度的正噪声会破坏该结果。
The “impossibility of speculations” result implied by some models of information economics seems to follow directly from the strong assumptions concerning the information structure in the relevant models. This paper investigates whether the impossibility result hold when some “noise” is introduced into the information system in a “no trade” model. It is proved that when the degree of noise approaches zero, the noisy model converges to the impossibility result of the no-noise model. Yet it is shown that the introduction of some positive noise into the information system can disrupt the impossibility result in many applications. Journal of Economic Literature Classification Numbers: 024, 026.