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>The web says SQL is in fact TC contrary to your claim. Did you even read the link? You need extensions to make SQL Turing complete. Your replies indicate to m

by Grue3 8y ago

>The web says SQL is in fact TC contrary to your claim. Did you even read the link? You need extensions to make SQL Turing complete. Your replies indicate to me you lack the necessary theoretical background to discuss Turing completeness, since pure SQL not being TC is such a basic fact you don't need to look it up on the web. The fact that the entire tech stack is TC is not a proof that TC is needed for individual parts of the tech stack. Indeed, some of the components of the web stack, namely CSS, are not TC (no, please don't look it up on the web and come back with "CSS is turing complete" bullshit, they're clearly wrong because halting problem of CSS is decidable). By the way Turing machine doesn't involve human interaction, so all your examples that involve interactivity (UI loops) are outside of scope of this discussion. >What is preventing TC buying your language when the programs are bug free? There's no such thing as bug free program. When you need to execute arbitrary programs, not being TC buys you a lot of guarantees that can be useful.

dahart 8y ago
> When you need to execute arbitrary programs, not being TC buys you a lot of guarantees that can be useful. Please, elaborate! What are these useful guarantees? Can you name some? > Did you even read the link? I think so... the first sentence says you don’t need an extension. The linked Mandelbrot set example is “SQL:2008 conformant” and depends on “nothing”. https://wiki.postgresql.org/wiki/Mandelbrot_set https://wiki.postgresql.org/wiki/Mandelbrot_set Is that using an extension? > By the way Turing machine doesn’t involve human interaction, so all your examples that involve interactivity (UI loops) are outside of scope of this discussion. Okay, so Turing completeness doesn’t apply to GIMP or Animstack at all, right? That’s what I was trying to suggest before. ;) Your own stated reason for removing TC from Animstack was UI. Who says human input doesn’t apply? Alan Turing didn’t say that. Wikipedia says that interaction does apply: https://en.m.wikipedia.org/wiki/Turing_machine#Interaction https://en.m.wikipedia.org/wiki/Turing_machine#Interaction “In principle, it is possible to model this [interaction] by having an external agent read from the tape and write to it at the same time as a Turing machine...” > The fact that the entire stack is TC is not a proof that TC is needed No, it’s just proof that TC languages are common and useful, and that not many practitioners would agree that TC is a “bad thing”. > Indeed, some of the components of the web stack, namely CSS, are not TC So? What does it prove if a few parts are non TC, when so many of them are? CSS is for styling, not for writing programs, unlike Animstack and sed and the other examples you’ve been using. It tends to undermine your points a little bit to hold up CSS as an example of a non-TC language. I wouldn’t want to use CSS to compute things, so I don’t care if it’s Turing complete or not. For that matter, I don’t care whether any language is Turing complete, as long as I can get my work done easily, why should I? > no, please don’t look it up on the web Okay, I won’t. Just kidding, here’s the answer, not just a claim, but an implementation of Turing Completeness. So what’s clearly wrong about it? https://stackoverflow.com/a/5239256 https://stackoverflow.com/a/5239256 To be honest, I don’t care what’s wrong with it. Or with sed or any other language. Not in purist academic theory. I wanted to hear if there are practical reasons to care, but since you won’t answer and I haven’t heard any, then I don’t care.

by Grue3 8y ago

dahart 8y ago

> When you need to execute arbitrary programs, not being TC buys you a lot of guarantees that can be useful. Please, elaborate! What are these useful guarantees? Can you name some? > Did you even read the link? I think so... the first sentence says you don’t need an extension. The linked Mandelbrot set example is “SQL:2008 conformant” and depends on “nothing”. https://wiki.postgresql.org/wiki/Mandelbrot_set https://wiki.postgresql.org/wiki/Mandelbrot_set Is that using an extension? > By the way Turing machine doesn’t involve human interaction, so all your examples that involve interactivity (UI loops) are outside of scope of this discussion. Okay, so Turing completeness doesn’t apply to GIMP or Animstack at all, right? That’s what I was trying to suggest before. ;) Your own stated reason for removing TC from Animstack was UI. Who says human input doesn’t apply? Alan Turing didn’t say that. Wikipedia says that interaction does apply: https://en.m.wikipedia.org/wiki/Turing_machine#Interaction https://en.m.wikipedia.org/wiki/Turing_machine#Interaction “In principle, it is possible to model this [interaction] by having an external agent read from the tape and write to it at the same time as a Turing machine...” > The fact that the entire stack is TC is not a proof that TC is needed No, it’s just proof that TC languages are common and useful, and that not many practitioners would agree that TC is a “bad thing”. > Indeed, some of the components of the web stack, namely CSS, are not TC So? What does it prove if a few parts are non TC, when so many of them are? CSS is for styling, not for writing programs, unlike Animstack and sed and the other examples you’ve been using. It tends to undermine your points a little bit to hold up CSS as an example of a non-TC language. I wouldn’t want to use CSS to compute things, so I don’t care if it’s Turing complete or not. For that matter, I don’t care whether any language is Turing complete, as long as I can get my work done easily, why should I? > no, please don’t look it up on the web Okay, I won’t. Just kidding, here’s the answer, not just a claim, but an implementation of Turing Completeness. So what’s clearly wrong about it? https://stackoverflow.com/a/5239256 https://stackoverflow.com/a/5239256 To be honest, I don’t care what’s wrong with it. Or with sed or any other language. Not in purist academic theory. I wanted to hear if there are practical reasons to care, but since you won’t answer and I haven’t heard any, then I don’t care.