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quine





Before we put the motion 'that the motion be now put,' should we not first put the motion "that the motion 'that the motion be now put' be now put?" (Chairman of the Meeting of the Society of Logicians)
—anonymous

A term named by Douglas Hofstadter after the Harvard logician Willard van Orman Quine. It can be used either as a noun or a verb.
  1. Quine (noun). A computer program that produces an exact copy of itself (or, alternatively, that prints its own listing.) This means that when the program is run, it must duplicate (or print out) precisely those instructions that the programmer wrote as part of the program, including the instructions that do the copying (or printing) and the data used in the copying (or printing.) A respectable quine – one that doesn't cheat – is not allowed to do anything as underhand or trivial as seeking the source file on the disk, opening it, and copying (or printing) its contents. Although writing a quine is not always easy, and in fact may seem impossible, it can always be done in any programming language that is Turing complete, which includes every programming language actually in use.


  2. Quine (verb). To write a sentence fragment a first time, and then to write it a second time, but with quotation marks around it. For example, if we quine "say", we get "say 'say'"). Thus, if we quine "quine", we get "quine 'quine'", so that the sentence "quine 'quine'" is a quine. In this linguistic analogy, the verb "to quine", plays the role of the code, and "quine" in quotation marks plays the role of the data.

Related category

   • LOGIC