众所周知，在古典逻辑中，逆否对称性是永真公式。
As we know, contrapositive symmetry is the tautology in classical logic.
此外，本系统中的各组原始公理还是自足的，即如想推出只含某些函数符号的永真公式时只须使用相应的公理便成。
This system is self-suffient in the sense that if we wish to deduce an equality involving only some of the three functions, then we need only to make use of the corresponding axioms.
本文详细介绍了岩层真厚度计算公式，在袖珍计算器中进行计算程序编排的方法。
This paper introduces in detail the formula for calculating the true thickness of strata and the method for the programming of the calculation by use of the pocket calculator.
应用推荐