AI question - Surrendering?

[CaptainAL]

How about empires that are dead? I played in a game where I was at war with a dead empire and the empire played out to the end. I had to capture every planet, even though my score was over 20%. I wondered if this always applies to dead empires, or perhaps this empire's AI did not allow surrender to begin with? I think I checked the AI file and it did, but I do not remember for sure.