分式作用下的保持性

Preserval Property by Fraction

分 别研究了 分式理论 对最小（原 子）和最 大（饱和）模 型的保持 性，并给出 了分式 理论 在可数模型个数上 的变化的一个较

We study the preserval property of the minimal (atomic) and the maximal (saturated) model between the original theory and the fraction theory, then give an almost complete classification of the change of the countable models′ number between these two theories.