探讨原子公式集为有限集Sn时,二值命题逻辑F(Sn)中公式集Γ的所有结论之集D(Γ)的结构.利用F(Sn)中公式在可证等价意义下的一般表示,通过建立一个特殊映射,将F(Sn)中公式之间的合取∧、析取∨及否定 的运算转化为在可证等价意义下某集合的子集之间的求交∩,求并∪,求补′的运算.进而得到(1)对于A∈F(Sn),ΓF(Sn),给出了A∈D(Γ)是否成立的充要条件;(2)对于ΓF(Sn),给出了Γ是否相容的充要条件;(3)对于ΓF(Sn),在可证等价意义下,给出了D(Γ)中所含F(Sn)中公式的个数;(4)对于Γ1,Γ2 F(Sn),给出了D(Γ1)与D(Γ2)之间的关系;(5)对于A∈F(Sn),ΓF(Sn),在可证等价意义下,给出了D(Γ)中与A距离最近的公式.
Under the condition of limit set Sn consisting of atomic formulas,the structure of D(Г) which is the set of all conclusions of a given formula set F in two-valued propositional logic is discussed. By using the result, the general representation of formulas in F ( Sn ) in the meaning of provable equivalence, and making a special mapping, the operations of ∧,∨, among formulas change into operations of ∧,∨,'on a special set in the meaning of provable equivalence, and then several results below are acquired. ( 1 ) for A ∈ F( Sn), F F( Sn ), the necessary and sufficient condition of whetherA∈D(F) is given; (2) for Г F(Sn) ,the necessary and sufficient condition of whether F is consistent is given; (3) for Г F(Sn) ,the number of formulas of F(Sn) in D (Г) in the meaning of provable equivalence is given ; (4) for Г1, Г2 F( Sn ), the relation between D (Г1 ) and D(Г2) is given;(5) for A∈F(Sn),F F(Sn) , in the meaning of provable equivalence, the formula which is the nearest one to A in D(Г) is given.