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Artificial intelligence researcher, John McCarthy, has died. He was 84.

The American scientist invented the computer language LISP.

It went on to become the programming language of choice for the AI community, and is still used today.

Professor McCarthy is also credited with coining the term "Artificial Intelligence" in 1955 when he detailed plans for the first Dartmouth conference. The brainstorming sessions helped focus early AI research.

Prof McCarthy's put forward the idea that "every aspect of learning or any other feature of intelligence can in principle be so precisely described that a machine can be made to simulate it".

The conference, which took place in the summer of 1956, brought together experts in language, sensory input, learning machines and other fields to discuss the potential of information technology.

Other AI experts describe it as a critical moment.

"John McCarthy was foundational in the creation of the discipline Artificial Intelligence," said Noel Sharkey, Professor of Artificial Intelligence at the University of Sheffield.

"His contribution in naming the subject and organising the Dartmouth conference still resonates today."

Prof McCarthy devised LISP at Massachusetts Institute of Technology (MIT), which he detailed in an .

The computer language used symbolic expressions, rather than numbers, and was widely adopted by other researchers because it gave them the ability to be more creative.

"The invention of LISP was a landmark in AI, enabling AI programs to be easily read for the first time," said Prof David Bree, from the Turin-based Institute for Scientific Interchange.

"It remained the AI language, especially in North America, for many years and had no major competitor until Edinburgh developed Prolog."

In 1971 Prof McCarthy was awarded the Turing Award from the Association for Computing Machinery in recognition of his importance to the field.

He that the lecture he gave to mark the occasion was "over-ambitious", and he was unhappy with the way he had set out his new ideas about how commonsense knowledge could be coded into computer programs.

However, he revisted the topic in later lectures and went on to win the National Medal of Science in 1991.

After retiring in 2000, Prof McCarthy remained Professor Emeritus of Computer Science at Stanford University, and maintained where he gathered his ideas about the future of robots, the sustainability of human progress and some of his science fiction writing.

"John McCarthy's main contribution to AI was his founding of the field of knowledge representation and reasoning, which was the main focus of his research over the last 50 years," said Prof Sharkey

"He believed that this was the best approach to developing intelligent machines and was disappointed by the way the field seemed to have turned into high speed search on very large databases."

Prof Sharkey added that Prof McCarthy wished he had called the discipline Computational Intelligence, rather than AI. However, he said he recognised his choice had probably attracted more people to the subject.