The answer is the UNSC AI Matrix Compiler. Specifically the one Dr. Halsey designed.
This bit of information is located on Halsey's data pad in the level Composer.
English
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Ok yeah I'm probably not ready for heroic. Hit me with just a normal one
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You should be prepared for this one. What planet was John-117 born on?
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Eridanus 2
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Yup. Just a tip, the correct form is Eridanus II, but that's just me nit-picking.