Parallel evolutionary programming using Semantic Brain
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README.md

evolve-sbrain

This program uses a simple, highly parallel evolutionary algorithm to evolve computer programs in my language sbrain.

If you're looking to run the generated programs, take a look at sbic.

It is quite effective at evolving relatively simple algorithms. It is invoked with cargo run --release <config file>, where the config file looks like this:

mutations_per_generation = 3
initial_program_length = 8
max_runtime = 128
population_size = 32
inputs = [ [1],       [2],       [999]]
targets = [[1, 2, 3], [2, 3, 4], [999, 1000, 1001]]

This is the specification for a program that starts at the input, and prints the next two consecutive numbers. A sample run from this example is:

Generation     1 Cost  5079: .Sa.s-^a
Generation     2 Cost  2013: ..S,.s-^a
Generation    26 Cost  1011: ,..zS,.s-^a
Generation    30 Cost     6: ,..zS+.s-^a
Generation    53 Cost     3: ,..+S+.s-^a
Generation   101 Cost     0: ,.*+.+.s-^a
Program found after 101 tries.
,.*+.+.s-^a
Ran for 100 cycles and did not halt
[1] -> ,.*+.+.s-^a -> [1, 2, 3]
Ran for 100 cycles and did not halt
[2] -> ,.*+.+.s-^a -> [2, 3, 4]
Ran for 100 cycles and did not halt
[999] -> ,.*+.+.s-^a -> [999, 1000, 1001]

The optimal program, of course, is ,.+.+..

There are a number of sample configurations in sample-configs/. Try them out! Note also that the option legacy = true can be added to the config file to force the algorithm to use only the original 8 Brainf*** instructions. For instance:

Generation     1 Cost  2013: +,.,.--,,.
Generation     3 Cost  1011: ]+>,[.[.[>.
Generation     7 Cost    12: <<,+.++..
Generation     8 Cost     6: >,..+.
Generation     9 Cost     3: <<-,.++..
Generation  1675 Cost     0: <-<---+,.+.+.
Program found after 1675 tries.
<-<---+,.+.+.
Ran for 128 cycles and did not halt
[1] -> <-<---+,.+.+. -> [1, 2, 3]
Ran for 128 cycles and did not halt
[2] -> <-<---+,.+.+. -> [2, 3, 4]
Ran for 128 cycles and did not halt
[999] -> <-<---+,.+.+. -> [999, 1000, 1001]