TAK AI

by Joshua Achiam

Hello! Welcome to my Tak AI library! Currently the library does not support a graphical interface, and the AI can only be played against on the command line. I recommend you use the PTN viewer by Ben Wochinski to view games.

The library supports two main AI variants. One AI uses a minimax search with alpha-beta pruning and a heuristic value function I've devised by trial and error. This variant is Takai. The other AI uses a flat Monte Carlo method for evaluating possible moves. This variant is Takarlo.

Dependencies:

The Tak AI library is written in Lua.

To use it, you need to install...

1. The 'Torch' package (from torch.ch, which will also install Lua)

2. The 'threads' package (run 'luarocks install threads' after you have installed Torch).

That should be everything.

How to Play:

1. Navigate to the tak-ai directory and fire up Torch with the 'th' command in the command line.

2. Run the following commands to begin a game against the AI:

require 'tak_AI'

game = tak.new(5)	-- creates a new game of Tak on a board of size 5


-- let's load a partially played game
game:play_game_from_file('game.txt')


-- create a new minimax AI agent doing a depth 3 search
-- the second arg is the debug flag, so it'll give some info with each move
takai = make_takai_01(3,true)


-- create a flat Monte Carlo agent that takes 75s per move to think
takarlo = make_takarlo_01(75,true)	


-- begin a match against takai where the human goes first
-- arg1: game object
-- arg2: first player 
-- arg3: second player
fight_takai(game,human,takai)	

To issue commands to the game when it is your turn, give your move in PTN. PTN admits some ambiguity, so here is what is permitted:

• a1, fa1, Fa1 are all acceptable. (the first letter may be lowercase for placing walls or caps also.)
• a1>, 1a1>1, and 1a1> are acceptable.

(That is to say, as of a recent update, the game now permits all variants of PTN!)

The game outputs a visual to the command line that looks like this:

th> require 'tak_AI'
true	
                                                                      [0.0014s]
th> fight_takai(tak.new(3),human,make_takai(3,true))
fa1
   +---+---+---+
3  |   |   |   | 
   +---+---+---+
2  |   |   |   | 
   +---+---+---+
1  | b |   |   | 
   +---+---+---+
     a   b   c  
	
AI move: fa2, Value: 0.5, Num Leaves: 270, Time taken: 0.082605	
   +---+---+---+
3  |   |   |   | 
   +---+---+---+
2  | w |   |   | 
   +---+---+---+
1  | b |   |   | 
   +---+---+---+
     a   b   c  

a2-
   +----+---+---+
3  |    |   |   | 
   +----+---+---+
2  |    |   |   | 
   +----+---+---+
1  | bw |   |   | 
   +----+---+---+
     a    b   c  

Here, we see an exchange over three plies: the human enters fa1, placing a black stone at a1; the AI responds with fa2; the human then captures by moving its white stone at a2 on top of the black stone at a1. Stacks are written so that the bottom is on the left. Flats are denoted by 'b' or 'w'; walls by '[b]' or '[w]'; caps by '{b}' or '{w}'.

If you'd like to control the game more directly, I recommend you check out the source code, but the snippets you will be most interested in are:

game:make_move(a)

which tells the Tak game object to execute the move 'a' (which should be in PTN, but may also be an index corresponding to the PTN move -- but don't worry about that! there is some magic and duct tape here).

Also,

agent:move(game)

which tells the AI agent object to make a move in the game.

Using a GUI for Tak-AI

Tobias Merkle (asgardiator) wrote a GUI for playing the Tak-AI! An install script for the GUI is available in this library; running install.sh will download everything you need. A readme for his GUI is available here.

Misc.

###Some thoughts on Takai:

You probably should not play against the generic minimax_AI at depths greater than 4. The current implementation of the minimax search is fast enough to compete well on depth 4: from my experience, it takes somewhere on the order of 15 seconds to make a move on the 5x5 board, on average, and rarely more than a minute. But for games with many stacks, this can go up. Not sure how it does on 4x4, but probably just fine.

However, if you play against the killer_minimax_AI, depths up to 5 should play at acceptable speeds. It seems that the average move here takes around 30 seconds, and rarely more than a minute. The increased level of play may justify the slowdown.

###Some thoughts on Takarlo:

Takarlo will make better moves if you give it longer to think. Takarlo gets creative in ways that Takai doesn't. But it also sometimes misses what seems like the obvious move to make, and even makes clearly poor moves from time to time. I imagine that Takarlo will hold up poorly against human opponents, but I am not sure yet. Time will tell.

Last Thoughts

This is very much under active development! It's also extremely messy right now, and the README is only accurate as of 5/3/16. Cleaner code and a more useful readme will be made available in the future.