philosophicalbastard said:An AI's ability to copy and split itself was established in the book First Strike, so like many things from the expanded universe in Halo 4 they failed to properly explain it. The logic of Cortana doing it was having multiple insane AIs messing with the computer system of the Didact's ship was better than just one. Her saving chief from the nuke can be handwaved away with any number of Forerunner technologies such as teleportation or hardlight shields (she was controlling a hardlight bridge right before the nuke went off).
I'm aware of Cortana's ability to copy herself (something which I can assume she only did because of Rampancy considering the horrible state the Covenant AI was in). See your explanations would be fine if any of them were said to have happened. It's hard to just let the person assume Cortana could save Chief against Chief's will with the snap of a finger.