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The Hardest Logic Puzzle Ever is a logic puzzle so called by American philosopher and logician George Boolos and published in ''The Harvard Review of Philosophy'' in 1996. Boolos' article includes multiple ways of solving the problem. A translation in Italian was published earlier in the newspaper ''La Repubblica'', under the title ''L'indovinello più difficile del mondo''. It is stated as follows: Boolos provides the following clarifications: a single god may be asked more than one question, questions are permitted to depend on the answers to earlier questions, and the nature of Random's response should be thought of as depending on the flip of a fair coin hidden in his brain: if the coin comes down heads, he speaks truly; if tails, falsely.〔Note that the Random god in Boolos' puzzle is ''a god who acts randomly as either a truth-teller or a liar''. This is different from ''a god who answers 'yes' or 'no' randomly''. One usual trick in solving many logic puzzles is to design a (perhaps composite) question that forces ''both'' a truth-teller and a liar to answer 'yes'. For such a question, a person who randomly chooses to be a truth-teller or a liar is still forced to answer 'yes', but a person who answers randomly may answer 'yes' or 'no'.〕 ==History== Boolos credits the logician Raymond Smullyan as the originator of the puzzle and John McCarthy with adding the difficulty of not knowing what ''da'' and ''ja'' mean. Related puzzles can be found throughout Smullyan's writings. For example, in ''What is the Name of This Book?'', describes a Haitian island where half the inhabitants are zombies (who always lie) and half are humans (who always tell the truth). He explains that "the situation is enormously complicated by the fact that although all the natives understand English perfectly, an ancient taboo of the island forbids them ever to use non-native words in their speech. Hence whenever you ask them a yes-no question, they reply ''Bal'' or ''Da''—one of which means ''yes'' and the other ''no''. The trouble is that we do not know which of ''Bal'' or ''Da'' means ''yes'' and which means ''no."'' There are other related puzzles in ''The Riddle of Scheherazade''.〔 The puzzle is based on Knights and Knaves puzzles. One setting for this puzzle is a fictional island inhabited only by knights and knaves, where knights always tell the truth and knaves always lie. A visitor to the island must ask a number of yes/no questions in order to discover what he needs to know (the specifics of which vary between different versions of the puzzle). One version of these puzzles was popularized by a scene in the 1986 fantasy film ''Labyrinth''. There are two doors with two guards. One guard lies and one guard does not. One door leads to the castle and the other leads to 'certain death'. The puzzle is to find out which door leads to the castle by asking one of the guards one question. In the movie, the protagonist, named Sarah, does this by asking, "Would he (other guard ) tell me that this door leads to the castle?" 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「the hardest logic puzzle ever」の詳細全文を読む スポンサード リンク
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