Artificial Intelligence

Artificial Intelligence (or A.I.) in the field of gaming and computer science, refers to the intelligence of the machines and the effort to re-create human-like intelligence in Non-Playable Characters (NPCs).

In Sword Art Online, the system is generally known for having a mixture of NPCs with very advanced A.I. and NPCs with very poor A.I.

«Top-Down AI»
In the Sword Art Online Universe, a Top-Down AI refers to artificial intelligence built from a program atop an existing computer architecture. NPCs in SAO have top-down AI, meaning they are scripted to act in an exact certain way in response to a very specific stimulus.

When speaking to Top-Down NPCs in a quest, a player must listen to the NPC through the entire duration of the speech. If not, the quest does not proceed, as the Top-Down AI is scripted in a very basic, simplistic fashion.

Top-Down AIs work from an Answer, and wait to respond to a question. Some AI can even be scripted and modeled to mimic human behavior, to almost be indistinguishable  f rom a human. These AI simply have more data to process, and have learned to mimic behavior, to fit a personality. Yui is a prime example of a very advanced Top-Down AI.

«Bottom-Up AI»
Bottom-Up AI are AI that work in the opposite manner of a Top-Down AI, as they compute an answer when a question is given, rather than having a preset answer to a desired question. Unlike Top-Down AI, who learn by the "Ask A, so answer with B" method (being from the top question, down answer), Bottom-Up AI learn through "Learn B, and answer when asked A". In other words, it is a "true artificial intelligence," in the words of Kirito.

In the Sword Art Online Universe, the only known way to create a Bottom-Up AI is through the cloning of a human Fluctlight - creating an Artificial Fluctlight. An Artificial Fluctlight is the cloned quantum field (soul) of a newborn baby, which is later nurtured in a VR world.

List of known NPCs

 * Yui
 * Ruru - NPC on the 56th Floor who provides the secret of defeating the Floor Boss.
 * Tonkii - a Beast-type evil-god monster in Jötunheimr, which later turns into an NPC capable of transporting players on its back.
 * Cardinal System - in Project Alicization it was an autonomous program, which was used for regulating the virtual world, but later developed a consciousnesses of her own.
 * Underworld Residents