NashCoding Yet Another Artificial Intelligence Blog

24Jul/109

Tutorial – Evolving Neural Networks with SharpNEAT 2 (Part 2)

In part 1 of the tutorial, we setup a basic experiment to evolve a neural network to play Tic-Tac-Toe against a couple of hand-coded opponents. In part 2, we're going to create a competitive coevolution experiment where the networks evolve by playing against themselves.

17Jul/104

Tutorial – Evolving Neural Networks with SharpNEAT 2 (Part 1)

The Neuro-Evolution via Augmenting Topologies (NEAT) algorithm enables users to evolve neural networks without having to worry about esoteric details like hidden layers. Instead, NEAT is clever enough to incorporate all of that into the evolution process itself. You only have to worry about the inputs, outputs, and fitness evaluation.

This is a tutorial on how to use SharpNEAT 2, the second version of a popular C# implementation of the NEAT algorithm written by Colin Green. The source code for this tutorial is available here.

7Jul/104

Evolutionary Algorithms: The Little Things (Part 1)

I'm the kind of person who finds himself reading about a new technology or a cool algorithm, and tries to implement it based on the high-level description. Unfortunately, I don't always guess everything correctly, and sometimes the implementation turns out to not work; or it kind of works, but not as well as expected, which can be even worse.

A key example of this for me was when I read about Evolutionary Algorithms. At the core, it's sounds so ingeniously simple:

  1. Create a population of individuals
  2. Score the individuals based on some performance metric
  3. Kill off the weakest performers
  4. Create children from the surviving parents
  5. If not finished, go to #2

That's really it, right? I always thought so.

7Jul/103

Implementation of Sukhotin’s Algorithm

I just read an article on HackerNews about a little-known algorithm called Sukhotin's Algorithm. The algorithm takes a dictionary of words and tries to figure out what the vowels are, based on the assumption that vowels are typically next to consonants. This sounded really cool, so I downloaded a big list of English words and implemented it.