Why Setup is checked at max corner and Hold at min corner?

Setup is checked at the max corner because it's where the circuit operates slower, and we need to ensure that data arrives in time before the next clock edge. Delays increase in the max corner due to factors like higher voltage or temperature, which can lead to setup violations if not checked.

Hold is checked at the min corner because it's where the circuit operates faster, and we need to ensure that data doesn't arrive too early and overwrite the previous data. Faster switching in the min corner could cause hold violations if not properly analyzed.

So, setup is checked at max corner for worst-case delay, and hold at min corner for worst-case speed.