"PX Function"
By Steve Walters
ARCADIAN 1, no. 10 (Sep. 31, 1979): 81.


The following are my comments on the PX function:

The possibility of the PX function as a location sensor seems reasonable if you
only have to monitor whether a player (meaning a visible marker such as a BOX)
is at a given location or not.

I have enclosed a simple program which uses the PX(X,Y) function as a location
sensor in the manner of a trap being sprung.  Ten traps (explosive mines,
invisible enemy ships, etc.) are set randomly, and if the player moves over any
of the trap locations, he is trapped (caught, exploded, etc.).

I don't see how this function could be used in two-player games in general,
since only two conditions can exist: PX(X,Y)=0 or PX(X,Y)=1. In many games,
monitoring is needed for three functions: PLAYER #1 (black), PLAYER #2 (white),
and neither player.  This is the case with most board games.

Two-player games where both players have black markers could use PX to monitor
both players, since only one player can move at any one moment.

Also, PX could be used to monitor the intersection of two player markers if they
were reverse BOX markers.  Their intersection would then be white if the markers
are black, and the PX function would equal 0 when they intersected.

                                          Sincerely yours,
                                          [signed]
                                          Steven L. Walters

                                          556 Langfield
                                          Northville, MI 48167
