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> Home > The Corewar Newsletters > The '94 Warrior > Issue #2

February 17, 1994                                                     Issue #2
______________________________________________________________________________

First off, I would like to thank everyone for the interest and comments I have
received so far.  There was a large increase in the number of programs 
submitted to both of the experimental hills on Stormking, as well as to the
ICWS hill.  (If anyone wants to cover that hill, it's still available! ;-)

I also wanted to inform the masses about the program I used to create the
title for this newsletter.  It's called figlet, and you can get it by 
anonymous FTP to ftp.isu.edu:/pub/figlet.  It is also being discussed in the
alt.ascii-art newsgroup.

If you are unfamiliar with the '94 draft standard, you can learn more about
it by reading the FAQ for this newsgroup.  In addition, the program pMARS
includes a highly recommended tutorial on the new standard.  Feel free
to send me e-mail if you have any difficulty finding either of them, if you
need to have a corewar item mailed to you, or if you have any other questions.

The FAQ is available through anonymous FTP to rtfm.mit.edu, as
/pub/usenet/news.answers/games/corewar-faq.Z
______________________________________________________________________________

The ICWS '94 Draft Hill:

       Core size:	8000 instrucitons
   Max processes:	8000 per program
        Duration:	After 80,000 cycles, a tie is declared.
Max entry length:	100 instructions

The current ICWS '94 Draft hill:
 #  %W/ %L/ %T                      Name               Author   Score     Age
 1  42/ 30/ 28           Killer instinct         Anders Ivner     155       5
 2  38/ 25/ 37                     NC II       Wayne Sheppard     152      60
 3  37/ 25/ 38               Sphinx v5.1         W. Mintardjo     148      63
 4  35/ 25/ 39                     Snake       Wayne Sheppard     145      15
 5  43/ 43/ 14           Fire Storm v1.1         W. Mintardjo     143      66
 6  32/ 21/ 48                      ttti        nandor sieben     143      16
 7  42/ 42/ 16            Sylvester v1.0     Brant D. Thomsen     142      42
 8  32/ 23/ 45                    ttti94        nandor sieben     142      11
 9  35/ 28/ 38        JustTakingALookSee            J.Layland     141      59
10  43/ 45/ 12                    Rave 3        Stefan Strack     140      32
11  41/ 42/ 17                      SJ-4            J.Layland     139       9
12  39/ 39/ 22               Christopher       Steven Morrell     139       4
13  42/ 46/ 11                      Rave        Stefan Strack     138      43
14  39/ 41/ 20            Fast Food v2.1     Brant D. Thomsen     138      18
15  40/ 43/ 17       Beholder's Eye v1.7         W. Mintardjo     138      72
16  40/ 43/ 17               Ntttgtstitd         Simon Hovell     136       6
17  38/ 42/ 20                      tiny            J.Layland     134      40
18  39/ 47/ 14                Impurge 94     Fredrik Ohrstrom     132       2
19  40/ 49/ 10               Medusa's v6   Mintardjo & Strack     132      65
20  31/ 31/ 37                     CG IV     Brant D. Thomsen     131       1

New programs on the hill include two warriors from the KOTH hill:
"Killer instinct" and "Christopher"; as well as two new '94 warriors:
"Impurge 94" and "CG IV".

Despite the small number of new programs, the hill is really quite different.
Killer instict jumped right to the top of the hill ... probably due to all
the vampires it was able to prey upon.  It's also interesting that the
programs at the top of the hill tend to be those written in the '88
standard.  Again, this is a good reflection of the intensity of competition
on the KOTH hill.
______________________________________________________________________________

The ICWS '94 Draft Experimental Hill:

       Core size:	55,440 instructions
   Max processes:	10,000 per program
        Duration:	After 500,000 cycles, a tie is declared.
Max entry length:	200 instructions

The current ICWS '94 Experimental hill:
 #  %W/ %L/ %T                      Name               Author   Score     Age
 1  79/ 17/  4            Rave 3 (55440)        Stefan Strack     240       8
 2  75/ 11/ 14                   CG-X IV     Brant D. Thomsen     239       7
 3  74/ 23/  3           No Ties Allowed       Wayne Sheppard     226      13
 4  68/ 22/ 10                        BS            J.Layland     213      15
 5  65/ 23/ 12           testing testing     Fredrik Ohrstrom     208       3
 6  62/ 18/ 20                   BigImps        James Layland     206      16
 7  57/ 19/ 24               Frantic 0.9                A Lee     195      17
 8  59/ 33/  9                 bunker t3              P.Kline     184       4
 9  56/ 28/ 16           Road Hammer 0.3         Simon Hovell     184      14
10  53/ 25/ 23                 Iron Gate       Wayne Sheppard     181      12
11  52/ 36/ 12                     VJX-2         James Ojaste     169       1
12  36/ 53/ 11                 Tiny Ring            J.Layland     119      10
13  31/ 69/  0                  test 94X            Anonymous      93       6

14-20	No entries

A big thanks to James Ojaste for his entry:  "VJX-2".

Once again, this is an ideal hill for beginners -- you are _guaranteed_ to
get on it!
______________________________________________________________________________

HINTS and HELPS:

Before I begin with this week's hint, I need to thank Stefan Strack for
pointing out a mistake in the last issue of _The 94 Warrior_.  A 
                      MOV     #a, B
command is converted to
                      MOV.AB  #a, B
in the '94 draft, which will only move the "a" value of the instruction --
instead of the entire instruction.  You will need to explicitly specify that
the instruction be
                      MOV.I   #a, B
if you want an imp.

The following is an excerpt from the latest draft of the '94 redcode proposal.
I was actually planning to create a table similar to this for this issue's 
hint, but since one already exists, I'll just pass it along instead.

     A.2.1.2 ICWS'88 to ICWS'94 Conversion
     The default modifier for ICWS'88 emulation is determined according
     to the table below.
     
         Opcode                  A-mode  B-mode  modifier
         ------------------------------------------------
         DAT                     #$@<>   #$@<>   F
         MOV,CMP                 #       #$@<>   AB
                                 $@<>    #       B
                                 $@<>    $@<>    I
         ADD,SUB,MUL,DIV,MOD     #       #$@<>   AB
                                 $@<>    #       B
                                 $@<>    $@<>    F
         SLT                     #       #$@<>   AB
                                 $@<>    #$@<>   B
         JMP,JMZ,JMN,DJN,SPL     #$@<>   #$@<>   B
         ------------------------------------------------

>From now on, I will explicitly be specifying the moderator for all the 
instructions I supply in this newsletter -- which is probably a good idea when
writing '94 warriors as well.  I have found that forcing yourself to 
explicitly think about what modifier each instruction needs not only eases 
the development of '94 warriors, but can also be useful for generating ideas 
as well.

                           *  *  *

Since I'm already on the subject, this issue's hint will be on imp-rings and
spirals.

For those of you that are unfamiliar with exactly what imps, imp-rings, or
imp-spirals are, here is a copy of the explanation in the FAQ:

	Imp - Program which only uses the MOV instruction.
        	   example  MOV 0, 1
	       or
        	   example  MOV 0, 2
                	    MOV 0, 2

	Imp-Gate - A location in core which is bombed or decremented
	   continuously so that an Imp can not pass.  Also used to describe
	   the program-code which maintains the gate.
	           example   ...
        	             ...
                	     SPL 0, <example
	                     DAT <example, #0

	Imp-Ring - A minimal Imp-Spiral.
        	    d        EQU (coresize+1)/3
	            A        MOV 0,d   ; copy self to B
        	    B        MOV 0,d   ; copy self to C
	            C        MOV 0,d   ; copy self to A+1

	Imp-Spiral - An Imp-like program with two or more processes supporting
	   each other.  A three-point spiral, with six processes running in
	   this sequence:
	            d        EQU (coresize+1)/3
        	    A        MOV 0,d   ; copy self to B
	            B        MOV 0,d   ; copy self to C
        	    C        MOV 0,d   ; copy self to A+1
	            A+1      MOV 0,d   ; copy self to B+1
        	    B+1      MOV 0,d   ; copy self to C+1
	            C+1      MOV 0,d   ; copy self to A+2

As Paul Kline has pointed out several times in this newsgroup, imp-rings and
imp-spirals for a core of size M can be created by using steps the size of any
number that is a divisor of M*N+1, where N is an integer at least as great as
one.

Several people, including myself, had been under the misconception that if the
number M+1 is prime, than a core of size M will have no true imp-spirals
possible.  This is, however, not case.  For example, even though the number
55441 is prime, it is still possible to generate a 13 point imp-spiral in a
55440 size core because 55440*8+1 = 443521 = 13 * 34117.

For your convenience, I have listed the five smallest possible imp-spiral
sizes and steps for some different core sizes.

For a core of size 8000:

        Point   Step
        -----   ----
          3     2667
          7     1143
          9      889
         11     5091
         13     3077

For a core of size 55440:

        Point   Step
        -----   -----
         13     34117
         17     35873
         19     29179
         23     38567
         29     21029

For a core of size 8192:

        Point   Step
        -----   -----
          3     2731
          5     3277
          7     3511
          9     3641
         11     2979

There have been some interesting recent developments in imp-spiral usage.  A
"standard" imp-spiral (which is the type discussed in the FAQ) can be killed
by having your code decrement the B-field of a given location in the core
every turn.  (Code specifically designed to kill imps, imp-rings, or
imp-spirals is also referred to as an imp-gate.)  However, with the advent of
Cannonade (by Paul Kline), it was revealed that this decrementing is
insufficient for stopping _all_ imp-spirals.

Cannonade, for instance, has a "non-standard" 2668 imp-spiral followed closely
by a "standard" 2667 imp-spiral.  When the 2668 imp-spiral dies on the
imp-gate, it leaves behind an instruction to replace the missing instruction
that occurs when the 2667 imp-spiral hits the gate.  As a result, the 2667
imp-spiral is able to "pass through" the gate.  There were also two 2668
imp-spirals posted by Pierre-Etienne Moreau (P.E.M. & E.C.) in early November
of 1993 that had some success over-writing gates through the use of varied
distances between processes.

It is possible to stop any of the above mentioned imp-spirals by using an
imp-gate such as the following:

              start   SPL.B   0, <-10
                      DAT.B   <-11-2668, <-11

(Simply remove the ".B" modifiers if you are using the '88 standard.)

This code will kill any "2668" step imp-spiral, but could be over-run by an
imp-spiral with a different step ... such as a "1144" (7 point) imp-spiral.
In fact, to the best of my knowledge, it is _impossible_ to use the '88 (or
current '94) standard to create an imp-gate that will stop all possible
imp-spiral combinations.

However, with the current draft of the '94 standard, there are other options
available instead.  The imp-gating method I have had the most success with is
by using the ">" operand to continuously increment the B-field of a given
location in the core.  This causes the imp-spiral to move an instruction
past the point where it is supposed to, thus leaving a gap in the imp-spiral.

For an example of this technique, take a look at the following imp-gate:

              start   SPL.B   0, >-20
                      DAT.B   <-11, >-21

The location twenty instructions before "start" is continually being
incremented, so any "standard" imp-spirals will be killed here.  However, if a
gate-crashing imp-spiral gets past this location, it will also need to get
past the location ten instructions before "start", which is being decremented
every other turn.  Since the gate-crashing imp-spiral will tend to be quite
fragile when it reaches the second location, the decrementing will usually be
enough to finish it off.

While this gate will stop the three special imp-spirals mentioned above, it is
still possible to create a series of imp-spirals that can (at least occasion-
ally) over-write it.  However, this gate does have an advantage over the '88
method in its ability to work independently of the step-size of the imp-
spiral -- as well as forcing the opponent to use more complex and less
dependable imp-spiral combinations in order to over-write it.

On a final note:  you can easily create a '94 imp-gate that will stop any imp-
spirals -- if the imp-spiral uses a "MOV.I 0, b" instruction instead of a
"MOV.I #a, b" instruction.  Simply have an imp-gate that continually
increments the A-field at a given location.  "Sylvester" uses this technique
quite effectively!
______________________________________________________________________________

Looking to the Future:

The lastest draft of the standard has been on soda.berkeley.edu for a couple
of weeks now (as /pub/corewar/incoming/icws94.0202.Z).  Take a look at it
and let the newsgroup know what you think.  There are some interesting 
additions to the former '94 draft standard.

Also, please submit your programs to the '94 hills.  We'd love to have your
best KOTH warrior on the standard '94 hill, and I've found that the best way
to learn the '94 standard is to take an '88 standard program and try to
improve it.  Not only will you get the additional challenge and enjoyment of
learning the new standard, but you will be better able to correct and critique
the latest drafts of the new standard when they arrive.

If you have any comments or questions about the '94 hills or the '94
standard that you think might be of general interest, please let me know.
Good luck, and happy computing!
______________________________________________________________________________

Brant D. Thomsen, Editor	   Snail mail:	1197 E. 6290 S.
(bdthomse@peruvian.cs.utah.edu)			Salt Lake City, UT  84121
University of Utah				U.S.A.
-- 
Brant D. Thomsen			The teaching of BASIC in schools
bdthomse@peruvian.cs.utah.edu		should be considered a criminal act.
(University of Utah)						- Dijkstra
2002-2005 corewar.info. Logo C. Schmidt