From: J G Coulthard <worc0092@sable.ox.ac.uk>
Newsgroups: sci.math
Subject: *CONNECT-4*
Date: 3 Feb 1996 01:43:49 GMT

Is it possible to force a draw in connect-4, or to force a win even?  &Is there
any known relevant algorithms?

Just in case the game is unfamiliar:

O O O O O O O  <-7 vertical columns of height 6
O O O O O O O  Player one (/two) has a stack of red (/yellow) counters.
O O O O O O O  The players take it in turn to put a counter in one of the
O O O O O O O  7 columns.  The columns fill up from the bottom to the top.
O O O O O O O  The game ends when either one player has 4 counters in a
O O O O O O O  line (horizontal/vertical/diagonal) - constituting a win for 
               that player - or when all the Os are full (i.e. after each  
               player has had 6*7/2=21 turns), this been labelled a draw.


[If this isn't enough already, how about generalizations to different board
sizes(in hyperplanes (-;)/different numbers of players/different lengths of
line-segments to win...etc.?!]


Thanks in advance,

John.

==============================================================================

From: jrr@atml.co.uk (John Rickard)
Newsgroups: sci.math
Subject: Re: *CONNECT-4*
Date: 3 Feb 1996 15:23:49 GMT

J G Coulthard (worc0092@sable.ox.ac.uk) wrote:

: Is it possible to force a draw in connect-4, or to force a win even?
: &Is there any known relevant algorithms?

I thought I'd read something about this.  A little Web browsing
confirmed that Victor Allis proved for his Masters Thesis at Vrije
University that the first player can force a win on a standard board;
his thesis is available at
ftp://ftp.cs.vu.nl/pub/victor/connect4.ps.Z.

Web addresses I found include

http://csclub.uwaterloo.ca/u/kppomaki/c4/  Keith Pomakis' Connect-4 Page
http://www.cs.vu.nl/~victor/               Victor Allis's home page

-- 
John Rickard