the concept of the syntactical truth degree of formulas in the system
L
*
is given in this paper.Then a series of the corresponding properties of the syntactical truth degree of formulas are discussed.Moreover
the similarity degree and pseudo-metric between formulas induced by syntactical truth degree are investigated.In addition
the continuity of the operations in the pseudo-metric space is proved.So then we can provide a possible framework for developing approximate reasoning based on the theory of syntax in the system