1324	 Answering English questions by Computer A Survey	 Fifteen experimental English language question-answering systems which are programmed and operating are described and reviewed. The systems range from a conversation machine to programs which make sentences about pictures and systems which translate from English into logical calculi. Systems are classified as list-structured data-based graphic data-based text-based and inferential. Principles and methods of operations are detailed and discussed. It is concluded that the data-base question-answer has passed from initial research into the early developmental phase. The most difficult and important research questions for the advancement of general-purpose language processors are seen to be concerned with measuring dealing with ambiguities translating into formal languages and searching large tree structures.
