This paper, on the basis of "classical unascertained set theory, proves the non - existence of "ideal proof composition forula, "thus it points out to all people that it is futile efffort to try to find out a"ideal proof composition formula"just like people try to make a perpetual machine or accomplish"equal dividing any acute angle"by three when people study expert system theory.

Based on rough sets and evidence combining theory, a general method of extracting the extension decision rules of probability information system is given.

This paper analyzes the problems of conflictive evidence combination with the Dempster-Shafer(D-S) theory,defines some concepts to be judged the extent of evidences conflict,such as evidence consistent degree, evidence conflictive degree,evidence conflictive intensity and evidence consistent/conflictive degree.

The mass function is determined by using fuzzy mathematics, and a belief matrix is produced according to the evidence combination rule.

The combined evidence gotten with the new combination rule has a better convergence characteristic than that gotten with the DS combination rule,which is helpful to the subsequent decision for target identification.

This paper puts forward that the Entropy Formula of the Mixed Perfect Gas doesn t apply to pure gas,and gives a kind of explanation about Gibbs paradox.