I have a question regarding operations. I use the following definition: An operation * on A is a rule which assigns to each ordered pair (a,b) of elements of A exactly one element a*b in A.
This implies that a*b must be UNIQUELY identified. I don't exactly understand what it means.
For example: Is subtraction an operation on integers?
If a and b are integers then for example:
for (3,2): 3-2=1
for (4,3): 4-3=1 is the same as for (3,2)
Does it mean that subtraction is not an operation on integers?