https://github.com/yasulab/pynect4

Connect 4 Game with Python
https://github.com/yasulab/pynect4

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Connect 4 Game with Python

• Host: GitHub
• URL: https://github.com/yasulab/pynect4
• Owner: yasulab
• Created: 2011-02-15T12:34:20.000Z (almost 14 years ago)
• Default Branch: master
• Last Pushed: 2011-02-25T17:23:57.000Z (over 13 years ago)
• Last Synced: 2024-10-10T09:24:04.641Z (about 1 month ago)
• Language: Python
• Homepage:
• Size: 102 KB
• Stars: 1
• Watchers: 2
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README

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README

        
Title: PyConnect4

Author: Yohei YASUKAWA

Date: Feb. 25

How To Run

-----------

To run PyConnect4, you need to get python 2.6.x.

After getting the python, you can run the program by typing following command.

	$ python main.py WIDTH HEIGHT CONNECT_N PLAY_STYLE FIRST_PLAYER

	

WIDTH	= a width of board

HEIGHT	= a height of board

CONNECT_N = How many connects players should get to win

PLAY_STYLE:

	'human' = Player vs. Player

	'cpu' 	= Player vs. CPU

FIRST_PLAYER:

	'p1' = Player1(you) plays first.

	'p2' = Player2(human or cpu) plays first.

	

Example Command:

	$ python main.py 3 3 3 cpu p1

How AI Runs

-----------

This AI program runs on a mini-max algorithm,

and scores in the following way.

- If a terminal node shows you win, return 1.

- If a terminal node shows you lose, return -1.

- If a terminal node shows drawn game, return 0.

But the basic mini-max algorithm spends so much time

if a board is equal to or larger than 4x4 with connect 3.

So, I added the algorithm that do pruning a tree that

is needless to calculate, with alpha-beta algorithm.

Thanks to the algorithm, this AI calculates how to

win with less time than before. But there are still

2 concerns on this AI.

First, if AI thinks that it never wins in the given

board, it gives up playing a game. For example,

if a given board is 4x4 with connect 3 and AI is the

last turn, it notices that it cannot win by calculation.

So, all possible moves have -1 score; thereby,

AI gives up and always inserts a coin at the most left,

which seems that AI does not run appropriately.

In other words, if using same board with connect 3 and

AI is the first player, you never win the AI.

This problem is caused by simple scoring function,

return 1, 0, or -1. So, revising the function will be

able to solve the problem.

The other concern is that if a board is much larger,

such as 5x5 with connect 4, the AI does not work

appropriately because AI needs tons of time to

calculate next move. Even though alpha-beta algorithm

helps to reduce calculating time, it is still difficult

for AI to calculate tons of trees. In particular, it needs

tons of time at the first turn in the game.

If I will solve the problem, I will make AI able to evaluate

not-terminal trees. For, AI does not have to calculate up to

terminal nodes if it can evaluate the non-terminal trees. So,

with that function, AI will be able to much larger board.

In conclusion, implementing those functions to this AI

will make it smarter and more functional, and users can

play connect4 with more various board size they need.