THE STRING GAME


If you would like to encourage efforts of this type in the educational
software world, please send $10.00 to:

                    Invisible Light Software
                    21 Grand Street
                    Warwick, New York  10990
                    (914)986-6255

A version of this game is also available on request for the Commodore
64, by mail.  Send Diskette, with return address.





THEORY:
     This game is based on techniques used in the CEMREL Math Program.
It encourages logical thought process while strengthening basic math
skills.  Its use of Venn Diagrams and set theory prepares students for
algebra, as well as any course where logic and deduction is required.


OVERVIEW:
     There are two levels in this game.  The first level involves
twelve sets, the second involves fifteen sets.  The sets include:

     1)   Multiples of 2
     2)   Multiples of 3
     3)   Multiples of 4
     4)   Multiples of 5
     5)   Multiples of 10
     6)   Odd Numbers
     7)   Larger than 50
     8)   Positive Divisors of 12
     9)   Positive Divisors of 18
     10)  Positive Divisors of 20
     11)  Positive Divisors of 24
     12)  Positive Divisors of 27
*    13)  Positive Prime Numbers < 50
*    14)  Smaller than -10
*    15)  Larger than -10


* denotes only available in level 2.



     The gameboard itself is made of three intersecting circles,
labeled A, B, and C, respectively.

          The area where circle A intersects with circle B is labeled
          AB;
          
          the area where circle C intersects with circle A is labeled
          AC;
          
          the area where circle B intersects with circle C is labeled
          BC;
          
          the area where circles A, B and C intersect is labeled ABC.
          
          The area outside all three circles is labeled
          D.

     The computer selects one set EXCLUSIVELY for each circle from the
list of sets.  By testing numbers in areas of the gameboard, the
player may logically determine which set has been chosen by the
computer for a given circle.
     The game also allows the player to mark a set as the game
proceeds as Possible or Not Possible for a given circle.


PLAYING THE GAME:

     The player is first asked which level he or she wishes to play (
1 or 2).  The three circles are displayed on the gameboard screen and
a prompt appears:

                    COMMAND: N/C/L/S_

N    stands for Number test.
C    stands for Circle test.
L    stands for List of sets.
S    stands for Surrender.


TESTING NUMBERS:
To test a number press N <Return>.
Another prompt appears requesting the number to test:

                    Number:

Type the number you wish to test and press <Return>.
The last prompt appears requesting the area you wish to test the
number in:

                    Area:

Type the Area (A, B, C, AC, AB, BC, ABC or D) and press <Return>.

If the number is found in the area you have chosen it will appear in
the area.  If the number is not found a "Sorry!!!" message is
displayed in the lower left hand corner of the screen. (See the
discussion of important ideas at the end of this document.)


VIEWING SETS, MARKING SETS:
You may view the list of sets from the COMMAND: prompt by pressing  L.

Each set name is given a number from 1 through 12 (level 1), or 1
through 15 (level 2).  These numbers are the SET#'s.

If you do not want to mark sets press N at the prompt:

                    Do you want to mark sets?(Y/N)

Press a key, and you will be returned to the gameboard.



If you want to mark a set as Possible or Not Possible press Y at the
prompt:

                    Do you want to mark sets?(Y/N)

A prompt appears for the set number you wish to mark:

                    Set#:

Type the number of the set you wish to mark and press <Return>

The next prompt requests the status:

                    (P)ossible, (N)ot Possible?

The last prompt requests which circle you wish to indicate this status
for:

                    For which circle: (A, B, or C)?

Type your choice and press <Return>.

If you are done marking sets, press <Return> at the Set#: prompt and
you will be returned to the game.



TESTING CIRCLES:
Once you have determined that a given circle can ONLY contain a
particular set you may test the circle.

Press C for Circle test from the COMMAND prompt.
A prompt appears to request the circle you wish to test.

                    Choose Circle (A, B, or C):

Type the circle you  wish to test and press <Return>.

Another prompt appears to request the set you wish to test in the
given circle.

                    Set#:

Type the number of the set you wish to test and press <Return>.

If the circle does contain the set you have tested, the set will
appear in the circle .  If not, the "Sorry!!!" message will be
displayed in the lower left corner of the gameboard.

When all three circles have been correctly guessed, the board displays
all three sets and asks if you want to play again.



SURRENDER:  or the coward's way out.

If you find yourself completely stumped, you may end the game by
selecting S from the COMMAND: prompt.  The three sets are displayed
for each respective circle.


IMPORTANT IDEAS:

Exclusive:     A set will only be in one circle.  A circle may contain
               some MEMBERS of another set, though, in areas where it
               intersects with another circle.
               
               For example, Multiples of 2 (2,4,6,8,10...) contains
               all of the Multiples of Four (4,8,12...), etc.
               
               If Circle A contains Multiples of Two, and Circle B
               contains Multiples of Three, and Circle C contains Odd
               Numbers then ONLY Area AB will contain a 6.

When testing numbers, remember that you are testing for the only area
where a number can exist.


Sorry!!!:      The "sorry" message can mean the following:

1.        The number does not appear ONLY in the tested area.  See
          Exclusive, above.

2.        The number  does not appear in any of the Circle Areas (it
          is outside the three circles, area D).

You may test numbers in Area D by typing N for Number: and then D at
the Area: prompt.



HELPFULL IDEAS:
     Test the same number in many areas until it appears in one of the
circle areas.  Once you have a number in one of the areas you can
start to test numbers which are not in adjacent areas, thereby
eliminating set choices.