COMMUTATIVE LAWS. Two laws relating to numbers, one with respect to addition and the other with respect to multi plication. These laws may respectively be defined symbolically as follows: a+b= b+a, and ab= ba; that is, the terms or the factors may have their order changed in any way we choose. The laws do not hold throughout the entire range of mathematics, however. For example, the commutative law of addition does not hold for the conditionally convergent series I — -}- . . . .