XKCD posted a logic program titled Blue Eyes: The Hardest Logic Puzzle in the World. The problem got posted to reddit, and of course a large argument erupted in the comments thread about how the question doesn’t make sense, the solution doesn’t make sense / doesn’t work / is flawed / etc. etc. etc.
Rather than futilely attempt to make myself heard above the din, I’m writing this post which explains what the solution is, how you get to the conclusion, why it is in fact correct, and why the guru’s statement is necessary.
Read more…
Evolution, Logic
In mathematics, a fixed point is a value of a function that maps to its self. In other words, x is a fixed point of a function f if f(x) = x.
According to Kleene’s recursion theorem, fixed points exist in every programming language; i.e. in every programming language, there is at least one program (actually infinitely many, trivially different from each other.) the output of which is an exact duplicate of the program.
Attached you will find a fixed point program written in perl.
Read more…
Computer Science, Programing
At a philosophical discussion last night, we read “Jipi and the Paranoid Chip” by Neal Stephenson (Which, I just noticed, was posted to reddit 9 days ago, and got 1 up vote and 1 down vote. WTF?). If you’ve never read anything by him, I suggest you stop right this moment, go out and buy Cryptonomicon, Snowcrash and the Baroque Cycle, and do nothing until you’ve read them all.
The story is about a piece of software that was evolved to be indistinguishable from a paranoid schizophrenic. In the course of discussing the plot, someone asked if the paranoid schizophrenic chip would pass the Turing Test, with their inclination being no, it couldn’t.
Read more…
Computer Science, Metaphysics, Philosophy
The paradox of the heap, also known as the Sorities Paradox (from the Greek word for heap), is a paradox revolving around the problem of vagueness.
In its classical formulation, the paradox is expressed as follows:
One grain of sand is not a heap.
If one grain of sand is not a heap, adding one grain of sand will not make it a heap.
So two grains of sand are not a heap.
So three grains of sand do not make a heap.
…
X grains of sand do not make a heap.
Therefore, 10,000 grains of sand do not make a heap.
The form of this argument boils down to:
X grains of sand are not a heap.
If X grains of sand are not a heap, adding 1 grain of sand will not make it a heap.
(Some arbitrary large number of grains of sand) do not make a heap.
Read more…
Computer Science, Evolution, Musings, Philosophy, Vagueness
You’ll have to forgive me, as the first part of this is reconstructed from memory, from a paper I read several months ago.
Lets do a little thought experiment.
Read more…
Mathematics, Musings