关键词: 多值逻辑, Sheffer函数, 准完备集, 最小覆盖

Abstract: Multiple-valued logic is the logic that has more than two values.One important problem in multiple-valued logic completeness theory is the decision of Sheffer function，which depends on deciding the minimal covering of the precomplete classes.In deep research on the Sheffer function in partial four-valued logic，the determinant algorithm of Sheffer functions in partial four-valued logic is given，which is according to the minimal covering of its precomplete classes.This algorithm can determine all Sheffer functions in partial four-valued logic.

Key words: multiple-valued logic, Sheffer functions, precomplete sets, minimal covering