On Wed, Dec 05, 2001 at 04:55:04PM -0800, Tom Holub wrote:
> This shows a lack of understanding of netrek dynamics. First of all,
> phaserlocking isn't that hard, and humans do it better than computers,
> because humans do fuzzy things better than computers. If you feed a
> computer bad data (as the netrek server does with cloakers), it will
> take an enormous amount of programming effort to make it perform as
> well as a human would.
Just to show you that I'm not pulling shit out of my ass.
Consider the 'bad data' sent to the client:
#ifdef AS_CLOAK
if (pl->p_ship.s_type == ASSAULT) {
cpl->x=htonl(pl->p_x+(random() % 3000)-1500);
cpl->y=htonl(pl->p_y+(random() % 3000)-1500);
} else
#endif
{
cpl->x=htonl(pl->p_x+(random() % 2000)-1000);
cpl->y=htonl(pl->p_y+(random() % 2000)-1000);
}
Forget the AS_CLOAK thing for a second. The position is reported as
being up to 1000 units off on both the X and Y axis. The speed is
reported as 15 (or something else that is effectively useless). The
direction is left to be whatever it was before (i.e. no-op updates).
Pretty 'inaccurate', eh?
Now, picture three clients all on the same screen. All three clients
are robots that talk to each other using some other mechanism than
smessage(). If three clients are each getting a sensor reading of 'up
to 1000 units off on both the X and Y axis, but not more than that',
they can average these co-ordinates together to get a significantly
more accurate reading. How accurate? Well, the worst possibly
situation is that they are all off by exactly sqrt(100000 + 100000),
or around 1414.2 units. What is the chance of this happening? Well,
about 1 in 10**18.
What is the *probable* accuracy? This depends greatly on the random
number generator being used by ntserv, and how well distributed the
numbers are.
The latest code released from this list defines ZAPPLAYERDIST to be
390. Consider only one axis for a second, as the result of this
probability would only need to be squared to determine the probability
in two dimensions.
How many sets of 3 numbers are possible, given an integer space of
-1000...999? The answer is, of course, 2000**3, or 8 x 10**9.
How many sets of 3 numbers, in the integer space of -1000...999 add up
to a sum between -390 and 390? I'm feeling a little lazy, so:
(Yes, I divided the units by 10 to make it execute faster...)
$ perl -e 'for $a (-100 .. 99) {
for $b (-100 .. 99) {
for $c (-100 .. 99) {
$z = $a + $b + $c;
$z = -$z if $z < 0;
$i++ if $z < 39;
}
}
}
print "i = $i\n";
'
i = 2271808
Because it was divided by 10 three times, we need to multiply it by 10 three
times to come close: 2 x 10**9 (I even rounded down)
2 x 10**9
--------- = 1/4
8 x 10**9
On two axis', this is 1/16. Normally, on two axis', there is only 1/25.
In summary of the above, with the normal 'inaccurate' information,
there is a 1 in 25 (4.00%) chance that a cloaked ship will be revealed
by a phaser beam directed at the location actually sent by the server
from any direction, at the very longest range that the ship can fire a
phaser at. If three clients are receiving information, this can be
increased in our favour to 1 in 16 (6.25%). This may not seem like
much, but if you look carefully, this is a 56% increase in accuracy
under extreme conditions.
The 'extreme conditions' are, if we are exactly one phaser length away
from his actual position (in any direction), the percentage represents
the chance that we will be able to reveal him by only averaging the
co-ordinates that are available to us, and firing at that point. At
exactly one phaser length, the damage will be 0. (This is assuming
that we do not possess knowledge that he is exactly one phaser length
away... such knowledge would greatly increase our odds... :-) )
Under more realistic situations, he will often not be exactly one phaser
length away. He may be more, or he may be less.
How to narrow it down? Well, if you have one set of co-ordinates, the
greatest probability to hit him on the first shot is achieved if we
can be certain that he is not on our 'other side'. As the server will
report him +/-1000 units, the server must report him as at least
2000-390-390 units away in order for us to maintain the greatest odds
of hitting him. (He is then at least -389..1220 units from us, all
within the range of our phaser)
If three clients receive three different sets of co-ordinates, we can
reduce the 2000-390-390 units for the closest reported set of
co-ordinates by the difference between the furthest reported set of
co-ordinates. I.e. if one client reports him at a distance of 1000,
while another clients reports him at 1500, we can deduce that the
closest he could possibly be is 500 units, and the furthest he could
be is 2000 units.
Not coincidentally, the greater the range of co-ordinates sent to us
by the server, the more accurate our readings are. As an extreme
example, if one client is told that he is within 1000 units of a
point, and another client is told that he is within 3000 units of a
point, we can be 100% certain that he is exactly 2000 units from the
point. For my numbers, I am assuming an even distribution, and not
taking these additional numbers into account.
K... I'm getting tired, so I'm going to stop here. Suffice it to say
that quite a bit of information can be transferred to offer a fairly
large 'edge' in many situations. Exploitable patterns or not, the
computer has a decisive advantage in terms of reflex, calculation, and
organization. If it is programmed correctly, I see no reason why it
shouldn't be able to beat the best INL team at least some of the time.
I'm not saying it wouldn't take a lot of work. I'm saying that I can
inject my experience, and the experience of other players into it, add
a few lightning reflexes, split second team work organization that is
able to abruptly adjust such that the entire robot team changes to a
new tactic at the exact same instant if necessary, collective
information processing that approximates what some might consider
'cheating', etc.
If we actually did this, I don't think it would be too much blasphemy
to label the team 'The Borg'. One mind and all that. It would be
really cool to use custom graphics that were a little cold and
calculating for the COW client to offer an atmosphere of
omnipotence. "Resistance is futile. Prepare to be assimilated into the
collective."
Tom: Do you see the potential, even if you don't believe it would ever
amount to anything in your life time? And even if exploits were found,
watching the game and then make mild adjustments, or re-writing
sections of code to eliminate the exploit can be a very effective
method of "AI" evolution. If situations exist with several variables,
the robot teams could be set against each other with different
settings, and the top 50 performing settings could be randomly chosen,
or switched between during actual combat with human players. They
could be weighted according to success against different teams as a
method of emulating 'learning'. If the team begins to lose, it would
choose one of the other 50 pre-canned settings. It might be desirable
to weight the settings such that the robot team might be able to judge
one settings as perhaps offering a greater chance of success against
another setting upon observation of the strategies used by the other
team.
mark
--
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