波兰逻辑学家J.Lukasiewicz于1929年提出了另一种表示表达式的方法。按此方法，每一运算符都置于其运算对象之后，故称为后缀表示。这种表示法的一个特点是，表达式中各个运算是按运算符出现的顺序进行的，故无须使用括号来指示运算顺序，因而又称为无括号式。-Polish logician J. Lukasiewicz in 1929 that proposed an alternative method of expression. Click method, each operator is placed after its operand, so called suffix. This is a characteristic of representation, the expression of each operation is based on the order of operators appear, and there is no need to use parentheses to indicate order of operations, which is also known as non-bracket-style.