topological ring
A ring which is a topological space is called a topological ring if the addition, multiplication, and the additive inverse functions are continuous functions
from to .
A topological division ring is a topological ring such that the multiplicative inverse function is continuous away from . A topological field is a topological division ring that is a field.
Remark. It is easy to see that if contains the multiplicative identity , then is a topological ring iff addition and multiplication are continuous. This is true because the additive inverse of an element can be written as the product of the element and . However, if does not contain , it is necessary to impose the continuity condition on the additive inverse operation.