Alan Turing/Talk

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I'm curious, was the crime Turing was convicted of actually called "homosexuality," or was it called "gross indecency and sexual perversion"? -- Janet Davis

The crime was "gross indecency and sexual perversion." -- The Cunctator

The MacTutor biography linked in the article mentions blackmail as reason for his going to the police. Is there a reference to a more precise biography on the web? --AxelBoldt

For precision and accuracy, go to, Andrew Hodges' site. Unfortunately, he doesn't really discuss the trial in detail on the site, leaving the complicated story for his definitive book, Alan Turing: the Enigma. Suffice it to say there was an element of threatened blackmail, but it wasn't really about revealing that Turing was gay, and didn't really figure into the course of events. Basically, once the police got involved in Alan Turing's affairs (so to speak) for reasons that had little to nothing to do with homosexuality, they quickly discovered his homosexuality (he told them) and arrested him for it. The MacTutor biography has a lot of misleadingness. We should email Andrew Hodges ( to see if he's willing to contribute his encyclopedic entry ([1]) to here or Nupedia. -- The Cunctator

I hate to admit this, but I had to look up 'larceny' in the dictionary. Is that really a conventional word? -- JanHidders

Larceny is a form of theft, where property is taken unlawfully. The distinction between larceny and burglary is that in larceny the perpetrator does have lawful access to the property, but no lawful right to remove it (burglary involved an act of trespass as well as theft). Police officers are authorised to confiscate the possessions of people they have arrested, but must keep them in a specific location and return all the possessions when incarceration ends (unless a court orders otherwise). Keeping any of the possessions constitutes larceny. Embezzlement dffers in that the perpetrator has the right to remove the property for specific purposes, but removes the property for some other, unauthorised purpose. Larceny is a standard term in criminal law.

"he proved that there was no solution to the Entscheidungsproblem, also known in computer science as the halting problem." That's not true. While any instance of the halting problem can be transformed into the Entscheidungsproblem, that makes the halting problem a "subset", if you like, of the Entscheidungsproblem rather than its equivalent (Robert Merkel <rgmerk at mira dot net>)

Well, the "also known in cs as the halting problem" is oversimplified, I agree. However, it is true that Turing showed that the Entscheidungsproblem is unsolvable by reducing it to the Halting problem, so in a sense the two problems are equivalent. --AxelBoldt