
Building Fizzbuzz in Fractran from the bottom up - zeveb
http://malisper.me/2016/06/11/building-fizzbuzz-fractran-bottom/
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alexbock
Years ago I participated in a CTF where one of the challenges was to produce
Fractran programs that met certain requirements. They were relatively simple-
sounding things like computing the nth power of two, but even that is a bit of
a pain in Fractran. I initially tried something similar to this article,
manually compiling programs that use only the (Turing-complete) JZDEC
instruction on paper. Unfortunately, there was a length limitation which made
this approach impossible as it did not produce fraction lists nearly as small
as one can write by hand. I ended up finding it easier to write a program to
brute force all possible Fractran programs under the length limit until one of
them had the correct behavior than to actually write useful Fractran code by
hand.

~~~
aab0
That's interesting. How do you brute force all possible Fractran programs when
they take natural numbers? Did you have an upper limit like 10,000?

~~~
alexbock
The limit was quite small. There was a relationship between the number of
distinct primes you allowed to appear and the number of registers the Turing
machine it modeled had, but I don't remember the details. I don't recall the
choice of composites being very important. There was a pretty natural limit
that was apparent to me at the time but I've long since lost my Fractran
intuition.

