 The agencies which funded AI research ( such as the British government , DARPA and NRC ) became frustrated with the lack of progress and eventually cut off almost all funding for undirected research into AI . The pattern began as early as 1966 when the <unk> report appeared criticizing machine translation efforts . After spending 20 million dollars , the NRC ended all support . In 1973 , the <unk> report on the state of AI research in England criticized the utter failure of AI to achieve its " grandiose objectives " and led to the <unk> of AI research in that country . ( The report specifically mentioned the combinatorial explosion problem as a reason for AI 's failings . ) DARPA was deeply disappointed with researchers working on the Speech Understanding Research program at CMU and canceled an annual grant of three million dollars . By 1974 , funding for AI projects was hard to find . 
