Practice problem
Which of the following are flat ring maps?
Z→Q\mathbb{Z} \to \mathbb{Q}Z→Q
Z→Z(2)\mathbb{Z} \to \mathbb{Z}_{(2)}Z→Z(2)
Z→Z[1/2]\mathbb{Z} \to \mathbb{Z}[1/2]Z→Z[1/2]
Z→Z/2Z\mathbb{Z} \to \mathbb{Z}/2\mathbb{Z}Z→Z/2Z
Z→OK\mathbb{Z} \to \mathcal{O}_KZ→OK for any number field KKK
Type a concept, like “slope” or “photosynthesis”.