Meeting Notes

Present: Lee, Tom (scribe), Dave, Omri, Frode

Dave is moving on 🙁

Frode will be working on getting used to doing Clojush runs and getting back into writing Clojure code.

Omri is trying some things related to using Xerox machines for SIMD parallelism using stacked transparencies.
Unfortunately, adding new stacks in Clojush for just one example file is difficult, and therefore the easiest thing to do is to just change the global definition of the stacks.

ULTRA with many noops. This sounds interesting and potentially useful for allowing evolution to determine the correct amounts of noops.
- Adding noops effectively increases the alternation rate so that it can be set lower.
- Tom suggests using a fixed program size to encourage homology.
- A good project would be to look at evolving populations to see how much homology exists, especially comparing something like ULTRA with normal genetic operators.
If anyone wants to work on calc or other software projects, talk to Lee!

Implemented the change problem, which isn’t as difficult as it first appeared, since it may be possible to do without exec stack manipulations and only integer arithmetic.
- Tom will try some runs with only integers.
- Tom is interested in general in doing some sort of Linear Push with ULTRA, which may help with matching instructions that need structure with the right connections.
Bagging and other ensemble techniques are potentially interesting!

Pre-Meeting Agenda

Things Tom wants to discuss:

Using ML ensemble techniques to combine solutions from multiple GP runs into single solution
Feature selection might be useful, especially for lexicase!
The US Change Problem
- implemented and started testing
- no solutions so far, but some very close misses, such as some that miss 2 to 5 cases out of every 25
- It seems that ULTRA is having a hard time using semantic parentheses for instructions that need them, such as exec_y, exec_if, and exec_do*times.
  - I would be interested in trying some paren-free PushGP, where instruction groupings are somehow baked into instructions that need them. Or maybe, those instructions always start a paren, and only the ending paren can vary.
I’ve been timing the US Change runs, and am starting to get results as to which nodes of the cluster they are most efficient for.

Lee adds: