SHRDLU was a forerunner of later inventions in the field of robotics. As significant as this may be, the really interesting thing about SHRDLU was not its ability to play with actual blocks but its ability to follow instructions. [...] SHRDLU was different, however. It followed instructions given in English and could answer simple questions about the "block-world". Furthermore, it'd interact with the user to disambiguate instructions when necessary; it would inform you of the fact when you typed something inconsistent.