Abstract: Cancelled the first axiom L1) or the third axiom L3) of the classical formal logic system we established two kinds of quasi-formal deductive system, LG-Rand LG, respectively. In LG-R we proved that neither the deduction theorem nor the hypothetical syllogism (HS) rule held but a deduction theorem and an HS rule are obtained in a weak sense. We also proved that both the deduction theorem and the hypothetical syllogism(HS) rule hold in LG.

Key words:  , fuzzy logic system, deduction theorem, hypothetical syllogism(HS)rule, weak HS rule