Inside Multimedia 1995 August/IMM0895.ISO01.iso/share/os2/connect4/connect4.hlp

OS/2 Help File | 1994-04-23 | 17KB | 463 lines

ΓòÉΓòÉΓòÉ 1. How to Play Connect Four ΓòÉΓòÉΓòÉ

Connect Four is a two-player-game. On his turn, each player inserts a coin of
his colour in one of the columns. When a column is full, no more insertions are
allowed. The player who first manages to get four coins of his colour in one
line (either diagonal, horizontal or vertical) is the winner. In this game
either none, one or both of the players can be simulated by the computer.
The last option (both players are played by the computer) may not be too
thrilling for you, but during the development of the program it was a good
method to compare different valuation functions. We decided to leave this
option in the game, maybe in a future release you will be able to select
different valuation functions. If you had the source code, you could do this
already :-) For now, you can use it to check how two computer players play at
different levels. If you want to get more information about how the computer
plays, see How the Computer Finds a Move.

Note:  This program is freely distributed under the usual terms and conditions
for use and distribution of free software. If you are uncertain what this means
refer to Conditions for Using Connect Four.

Related topics:

 About the Authors
 Conditions for Using Connect Four
 Getting the Sources
The Connect Four Contest


ΓòÉΓòÉΓòÉ 2. Game Options ΓòÉΓòÉΓòÉ

You can select the identity (either Human or Computer) of both of the players,
and you can choose the player who is to begin. Any combination is possible. The
slider settings determine the level that the computer plays at. If the player
is human, the slider indicates the level at which the computer will calculate
hint moves for this player.
The higher the level, the better (and slower) the computer plays. As you will
find out quickly, it's no task to win against the computer when it plays on a
level below four. And it's no fun to play when the level is above seven
(because the computer decision takes too long - and you will not be able to
win!).
If you want to know more about the way the computer calculates his moves,
please refer to How the Computer Finds a Move.

Related topics:

 Program Options
 How the Computer Finds a Move


ΓòÉΓòÉΓòÉ 3. Program Options ΓòÉΓòÉΓòÉ

Here you can select some options concerning the whole program:

Enable Sound
   To select this option, you need MMPM/2.

Animate
   Determines whether or not the coins drop visually. When sound is enabled but
   animation is not, there will be no sound when you insert a coin or start a
   new game.

Change Pointer
   If selected, the mouse pointer will appear in different shapes according to
   its position and to the state of the game.

Save Settings on Exit
   If you select this option, all settings, including the window position and
   size, will be saved automatically when the program ends. All settings will
   be saved in the file connect4.ini in the current directory.

Related topics:

 Game Options


ΓòÉΓòÉΓòÉ 4. Product Information ΓòÉΓòÉΓòÉ

This dialog gives you some (boring) information about the authors of this
program. Simply press OK to leave it.

Related topics:

 How to Play Connect Four
 About the Authors
 Conditions for Using Connect Four
 Getting the Sources


ΓòÉΓòÉΓòÉ 5. Help for the Menu Entries ΓòÉΓòÉΓòÉ

To get help for the menu entries, you can either choose one of the topics
listed below, or simply press F1 after selecting the menu entry you want to get
information about.

Menu entries:

 Help for File
 Help for Game
 Help for Options
 Help for Help


ΓòÉΓòÉΓòÉ 6. Help for File ΓòÉΓòÉΓòÉ

The following menu items exist:

Load
   Restore a previously saved game. The game options (player levels, starting
   player etc.) are not stored so that the current options will be taken.

Save
   Saves the current game in connect4.ini. You can restore it later and
   continue playing ...

Exit
   You may guess what happens if you select this menu item.


ΓòÉΓòÉΓòÉ 7. Help for Game ΓòÉΓòÉΓòÉ

The following menu items exist:

Start
   This menu item is only available at the beginning of a game and only if the
   computer has to make the first move. After selecting this menu item the
   computer will start its calculation to find a good choice for the first
   column to insert a coin.

Undo
   Gives you the possibility to rethink your last decision.

Hint
   The computer tells you which move it would select if it were in your place.

New
   Choosing this point will abort the current game. The game board will be
   cleared. If the player who is going to start (see Game Options) is the
   computer you have to choose Start afterwards to begin the game. If the
   starting player is human you can drop the first coin immediately after the
   board is cleared.


ΓòÉΓòÉΓòÉ 8. Help for Options ΓòÉΓòÉΓòÉ

The following menu items exist:

Game
   Here you can select options concerning the computer level and related
   things. See also Game Options.

Program
   The dialog that appears if you select this menu item allows you to enable or
   disable some options concerning the appearance of the program. See also
   Program Options.

Save
   Here you can save the current options to the file connect4.ini. You also
   have the opportunity to save the options every time you quit the program.
   For this see Program Options.


ΓòÉΓòÉΓòÉ 9. Help for Help ΓòÉΓòÉΓòÉ

The following menu items exist:

Help Index
   This brings up a list with more or less interesting information about the
   program Connect Four.

General help
   This help screen will explain how to play Connect Four.

Product Information
   This displays a short information about the program and its authors. If your
   curiosity is not satisfied concerning this item, you can also refer to the
   Product Information, and, if even this does not satisfy you, furthermore to
   About the Authors. This should do.


ΓòÉΓòÉΓòÉ 10. How the Computer Finds a Move ΓòÉΓòÉΓòÉ

Here you will find information about the algorithm that calculates the
computer's choice if it is its turn to insert the next coin. This is only a
brief description. For more information look for books dealing with "Game
Theory", a subsection of Artificial Intelligence. Especially if you speak
German I strongly recommend you to read an article in the German magazine
"c't", August 1989, page 114, called "Dame spielen". Although the game
described there is not Connect Four, the explanation of the methods for this
kind of AI was totally enough to develop this program. This should hold for any
other game that is similar to Connect Four, that is any game where the computer
has a variable but finite number of possibilities to make his next move.

The current game status is saved in two identical board structures, one to
display the board and the other for the computer's calculations. In this second
board it can insert coins to test the results of its imaginary moves. (It was
necessary to have two boards because when the window is updated during the
calculation, it should still display the "real" situation on the game board and
not the state of the computer's calculations.) When the computer is going to
move, it inserts a coin in a column of "his" board and checks if it has won
(inserting one coin is called a "half move"). When it has won, it decides this
move to be a good one and therefore will also execute it in the "real" board.
Normally, this does not occur too often, so it has to check what will happen
after this move. It simulates an opponent's move, checks if the opponent has
won, and so on. After the computer has reached the recursion limit, it will
validate the situation displayed on the game board. These values are returned
recursively, and after having checked all game situations, it will select the
column with the best valuation and execute this move in the real game board.
The level selected for the computer is directly related to the calculation
depth, i. e. after how many of these "half moves" it will stop to recursively
insert coins. This limit is necessary because when one of the players inserts a
coin, the other player normally has seven possibilities to answer this move,
and thus the computer will take seven times longer to calculate when the level
is increased only one step. There are methods how to reduce this (they will be
explained in game theory books or articles), but experience shows that even
with these methods the computing time will be three to four times longer when
the level is increased one step.

Note:  When you have enabled the sound option and when you play at a level
above four, you will sometimes hear a laughter. This indicates that the
computer knows that he will win no matter what you do afterwards (you can give
up then!). Just a nastiness towards you:-).

Related topics:

How to Play Connect Four
About the Authors
Conditions for Using Connect Four
Getting the Sources
The Connect Four Contest


ΓòÉΓòÉΓòÉ 11. About the Authors ΓòÉΓòÉΓòÉ

The program was written by Nicole Greiber and Ralf Seidel. Both are currently
students of mathematics at the BUGH Wuppertal (Bergische UniversitДt
Gesamthochschule Wuppertal). Wuppertal is a small town in Germany near Cologne.

You can reach us via eMail (InterNet):

    [e-mail]

    [e-mail]

 or via Snail Mail:

        Ralf Seidel               Nicole Greiber
        WБlfrather Str. 45        BrБningstr. 6
        42105 Wuppertal           42119 Wuppertal
     Germany                   Germany

 Any kind of mail is welcome, may it be hints, comments, wishes for future
 releases, bug reports, corrections concerning our English or (less welcome)
 complaints. In one word: Drop us a note, and we'll be happy!

 Credits

 o Katharina             for her patience, help and understanding.

 o Olaf                  for his continuous complaints concerning the game's
                         outward appearance. He also let himself down to record
                         the "Insert" and "Game New" sounds with his "holy"
                         Mac.

 o Eberhard Mattes       for developing EMX, a great tool. He also helped us
                         with a problem regarding the .INI file.

 o Marc van Woerkom      for developing the "Multimedia for EMX" libraries.

 o Larry Salomon jr.     for publishing the Electronic Developer's Magazine. It
                         gave us lots of background information about OS/2
                         programming.

 o IBM                   one could say, without their fine operating system
                         this program would have been impossible to write.

  Related topics:

 How to Play Connect Four
 Conditions for Using Connect Four
 Getting the Sources


ΓòÉΓòÉΓòÉ 12. Getting the Sources ΓòÉΓòÉΓòÉ

If you want to obtain the source codes for this program, we would like you to
send us DM 40,- (or US-$ 25,- likewise). PLEASE do NOT send foreign cheques,
because the German banks charge about DM 10,- to change such a cheque, and we
guess that once you have decided to pay something, you would like to pay us and
not the bank.

Once you have got the source code, you will not get rid of us that quick. This
means that we will drop you a note when we have developed a new version of
Connect Four so that you can get the new sources if you like (a whole life
long!). Obviously, this includes that we store your address. If you do NOT want
this, please tell us, and we will not store it.

To compile the source codes, we have used EMX 0.8h (as you might have guessed
when you found the EMX DLL's). We did not try to use any other compiler, but we
do not think that it will work very well with the Borland C++ Compiler, because
some functions are defined and used in a different way. It should be easier to
use the IBM compiler, but there might also occur some minor problems. If you
want to compile the source code, the easiest way for you would be to get and
install the EMX compiler on your machine (if you haven't done this already). It
is FREE!, and it's available on various FTP sites, as for example ftp.cdrom.com
or in Germany at ftp.uni-stuttgart.de. If you want to compile the sound
features, you also need a multimedia package (but you don't need this if you
want to compile without sound). You can either use the mm4emx package written
by Marc van Woerkom (what we did), which is also available via FTP, or the
package included with the Developer's Toolkit Ver. 2.1.

Related topics:

 How to Play Connect Four
 Conditions for Using Connect Four
 About the Authors
 The Connect Four Contest


ΓòÉΓòÉΓòÉ 13. Conditions for Using Connect Four ΓòÉΓòÉΓòÉ

Copyright (C) 1994 by Nicole Greiber and Ralf Seidel

This program is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
PARTICULAR PURPOSE.

This program is free software; you can redistribute it if you make sure that
anybody who obtained a copy has the same rights as you have.

  1. You may copy this program like anything.

  2. It's not allowed to take money for this program itself. (A fee charged for
     handling etc. is allowed.)

  3. You may modify this program if any modification is well documented and
     this documentation is added to any copy you distribute. You may not change
     this part of the documentation.

 The source code of Connect Four is not free. Although this program is meant
 mainly as a programming example we think that some money given as an
 acknowledgement for our work is fair. If you have received the source code
 from us you are responsible that not more than three persons have access to
 these documents. (This means you are allowed to share the source code with two
 other persons of your choice.) Under no circumstances you are allowed to
 resell or distribute the source code. (Of course you may use small parts of it
 for your own programs and distribute them. In this context "small parts" means
 that some functions written by us may appear somewhere in your program.) If
 you want to know more about this, please refer to  Getting the Sources.

 If you have any questions about your rights please send us mail.

 Note:  We don't like all this talking about terms, conditions etc. so this
 page is surely not complete. Our main "message" is: Everything is allowed as
 long as the rights of anybody else are not affected and as long as you don't
 reduce our chances to earn some money by selling the sources.

 Any of the above restrictions can't be verified by us. At least we have more
 interesting things to do so we appeal to your fairness and to your conscience.

 Related topics:

 How to Play Connect Four
 Getting the Sources
 About the Authors


ΓòÉΓòÉΓòÉ 14. Plans for Future Versions ΓòÉΓòÉΓòÉ

We are planning to add or modify the following topics:

 o We want to add the possibility of selecting the board size and the number of
   coins that lead to victory.

 o We want to add the choice between several valuation functions.

 o We want to set the loudness of the sound to the value given by the MMPM/2
   volume button.


ΓòÉΓòÉΓòÉ 15. The Connect Four Contest ΓòÉΓòÉΓòÉ

When you have already read some parts of this online help, you might have
noticed that one of the difficulties in programming this game was to develop
the valuation function. This function is needed when the computer has
calculated a certain number of moves and did not find a winning or loosing
situation. A very simple method to validate a game situation is to give it the
value "0" when it did not lead to victory or loss. But when the game is played
at lower levels, its first phase will be quite boring. In some games a good
valuation function is very important and difficult (for example Chess), in
others it is trivial (for example when you only have to count a score). In
Connect Four you have to look at a given game situation and say whether it is
"good" or "bad".
If you want to know more about the theory behind this game, please read How the
Computer Finds a Move.

So, it's up to you! Send us YOUR valuation function, and it will take part in
the contest!

What the function should do:

 o It should return a number which is the valuation for a given game situation.
   You can limit this function to work only with the board size 7 columns and 6
   rows, but you can also use a variable board size.

 o It must not modify the game board. This means that it is not allowed to
   perform any moves and look what the situation is like two moves later.

 o It should be of reasonable speed. This means it should not take longer than
   one minute to calculate a move at level eight (when it's embedded into our
   Connect Four).

 o It should be written in EMX-C and should be as bug-free as possible. You
   should of course use all the naming conventions for the variables used in
   the program.

 We will make our judgement in regard to several factors: First of all, a very
 important fact is how good a function plays, so we'll let them play against
 one another on the levels 4, 5 and 6, as starting and as second player. But
 speed will also be regarded, and how interesting a game is (this is naturally
 a quite subjective topic).

 If you are interested in taking part in this contest, please have a look at
 the files in contest.zip. There you will find the Object files you need for
 compiling a little text-only version of Connect Four which you can use for
 testing purposes, and some sample valuation functions. If you have any
 questions, please contact us. Our addresses are listed in About the Authors.

 The most interesting thing: The prize!
 Well, we are no commercial software company, and writing programs is only our
 hobby. So please don't expect any expensive prizes. We only do this because we
 are curious to see good valuation functions, and because we want to know how
 good a computer can be in playing Connect Four. The one thing we can offer as
 a prize is a free version of Connect Four's source code. When you already got
 the source code from us, we will refund your payment. It is highly recommended
 to get the source code when you want to take part in this contest because for
 you it will be much easier to test and improve your function (and you can have
 a look at how we solved this problem). On information how to do this please
 refer to Getting the Sources. If the functions' author(s) don't refuse, we
 will release a version of Connect Four with the best functions.

 Date of expiry:
 This is a difficult topic. On the one hand, many people don't check the FTP
 servers too frequently, so it might take some time until a recent number of
 persons has got this program. Then, they might want to get the source code and
 get familiar with it. At last, they have to develop an idea for a nice
 function and program it. All these things take time.
 On the other hand, nobody wants to take part in a contest that will expire in,
 say, five years. And we don't want to wait for five years to check the
 results. So we think that a good expiry date will be the 31.12.1994. If
 anybody wants to send us a valuation function after this date, he is welcome
 to do so, but he will not take part any more. Of course we will inform all
 competitors about the results.

 We wish you much fun in developing and programming a good function!

 Related Topics:

 How the Computer Finds a Move
 How to Play Connect Four
 Getting the Sources
 About the Authors