Final answer:
Rayner is a key figure in the history of computer science and played a significant role in developing the natural language processing capabilities of Watson, an artificial intelligence program developed by IBM. Rayner's most famous contribution is Watson's victory in the game show Jeopardy!
Step-by-step explanation:
Rayner is a key figure in the history of computer science, specifically in relation to Watson, an artificial intelligence program developed by IBM. Rayner's most famous contribution is his role as a part of the IBM team that designed and built Watson, a program that gained worldwide attention for winning the game show Jeopardy! in 2011.
Rayner played a significant role in developing the natural language processing capabilities of Watson, which allowed it to understand and respond to questions in a human-like manner.