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Tupper's Self-Referential Formula

25 pointsby guavaabout 10 years ago

9 comments

cousin_itabout 10 years ago
Sorry, it ain&#x27;t self-referential unless it draws the picture around (0, 0).<p>I have no idea if that&#x27;s possible, though. Quines are possible in many programming languages, but the &quot;language&quot; of formulas without quantifiers is very limited. You can encode boolean logic, not sure about loops.<p>EDIT:<p>After some Googling, I&#x27;ve found a true self-referential formula: <a href="http:&#x2F;&#x2F;jtra.cz&#x2F;stuff&#x2F;essays&#x2F;math-self-reference&#x2F;index.html" rel="nofollow">http:&#x2F;&#x2F;jtra.cz&#x2F;stuff&#x2F;essays&#x2F;math-self-reference&#x2F;index.html</a><p>Note that it involves a recursive function definition, and part of the formula is generated by a fixpoint trick. I suppose that&#x27;s the simplest way to do this.<p>Also I really enjoyed the way he embedded a watermark into the formula, in a way that&#x27;s difficult to remove if you don&#x27;t know what you&#x27;re doing.
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xamuelabout 10 years ago
Self-referential formulas (truly self-referential ones, not involving the magic constant in Tupper&#x27;s famous one) are conceptually a consequence of Kleene&#x27;s recursion theorem, just like self-printing programs, but with a bit more caveats---obviously necessary caveats since it all depends on things like font choice etc. I spelled the details out in a paper [1] but there&#x27;s really nowhere appropriate to publish it, since it&#x27;s too trivial for a mathematician&#x2F;computer scientist audience and too tricky for a more general audience.<p>[1] <a href="http:&#x2F;&#x2F;semitrivial.com&#x2F;papers&#x2F;eqn.pdf" rel="nofollow">http:&#x2F;&#x2F;semitrivial.com&#x2F;papers&#x2F;eqn.pdf</a>
guavaabout 10 years ago
Numberphile video about this formula: <a href="https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=_s5RFgd59ao" rel="nofollow">https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=_s5RFgd59ao</a>
andrelaszloabout 10 years ago
Tupper, Jeff. &quot;Reliable two-dimensional graphing methods for mathematical formulae with two free variables.&quot; Proceedings of the 28th annual conference on Computer graphics and interactive techniques. ACM, 2001.<p><a href="http:&#x2F;&#x2F;www.dgp.utoronto.ca&#x2F;papers&#x2F;jtupper_SIGGRAPH2001.pdf" rel="nofollow">http:&#x2F;&#x2F;www.dgp.utoronto.ca&#x2F;papers&#x2F;jtupper_SIGGRAPH2001.pdf</a>
netrusabout 10 years ago
2^(106*17) only has 543 decimal-digits. So with a high likelyhood, the formular will plot &quot;this is so wrong&quot; in several basic fonts and languages for smaller n&#x27;s as an input.
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netrusabout 10 years ago
Hm, to me this feels scammy, like the &#x27;my-crack-is-nothing-but-the-32894239487th-prim&#x27;-trick. Count me impressed as soon as the plot also contains the input range ;)
raldiabout 10 years ago
A true quine graph would have to include the &quot;N&quot; constant, too.
alexdowadabout 10 years ago
How did &quot;Tupper&quot; figure this formula out??? Brute force?
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ExpiredLinkabout 10 years ago
No Tupperware? I&#x27;m disappointed.