"Until such time that computers at least match human intelligence in every dimension, it will always remain possible for skeptics to say the glass is half empty. Every new achievement of AI can be dismissed by pointing out other goals that have not yet been accomplished. Indeed, this is the frustration of the AI practitioner: once an AI goal is achieved, it is no longer considered as falling within the realm of AI and become instead just a useful general technique. AI is thus often regarded as the set of problems that have not yet been solved."