[Math] Subring of PID is also a PID

abstract-algebraring-theory

Given a PID (Principal Ideal Domain), is every subring of PID also a PID ?

Do I have to show that every subring of a PID is an ideal ?

Best Answer

Answer: no. $\mathbb{Q}[X]$ is a PID, whereas $\mathbb{Z}[X]$ is not. See this