NL:A LOOSE NATURAL DEDUCTION SYSTEM OF TEMPORAL LOGIC
NL:松弛时序逻辑自然推理系统

Owing to the characteristic of temporal logic,some rules of classical logic can't be used directly when doing temporal natural deduction. Though the N system shows us a solution of this problem in which all rules or deductions are divided into two types-verticality and horizontality, the two-dimensional mode also gives rise to some difficulties in deduction. This paper presents an NL system (a loose natural deduction system of temporal logic) that provides us with a unified view of all rules and-deductions.In fact,we can prove as well that NLis equivalent to N and that for every Ndeduction or proof there must exist an NL deduction shorter in length than the former.