November 4, 2013, in the morning , Professor Zhang Qi from the Taiwan Tsinghua University Department of Applied Mathematics, was invited by the Department of Management Science and Logistics to visit our school and made a presentation entitled "Unknown operator and standard state-space model ". Professor Zhang Qiang, Head of the Department of Management Science and Logistics, hosted the report. In the report, Professor Zhang Qi first introduced the concept of unknown and a conclusion given by Dekel, Lipma and Rustichini in 1998. He then introduced their research results in the standard state-space model. Finally he pointed out the concept of unknown can also be defined by limited logical system S4 . In addition, he also introduced a number of other research.