[Computer-go] ManyFaces swindled of victory?

David Fotland fotland at smart-games.com
Sat Nov 13 08:52:17 PST 2010


It is certainly true that strong programs today are weaker at semeai than
people of the same rating.  This must mean that the programs are stronger in
other areas than equal ranked people.  This gives me hope that when Many
Faces plays semeai properly it will get a big jump in strength.

 

David

 

From: computer-go-bounces at dvandva.org
[mailto:computer-go-bounces at dvandva.org] On Behalf Of terry mcintyre
Sent: Saturday, November 13, 2010 8:33 AM
To: computer-go at dvandva.org
Subject: Re: [Computer-go] ManyFaces swindled of victory?

 

Don, as you say, humans are very good at discerning patterns - and the game
of Go is all about patterns. 

 

Now, in some cases, the pattern-matching ability can lead humans astray, but
in other cases, it's a done deal. 

 

For example, we hashed over the concept of nakade a while back. These are
patterns which strong humans recognize at a glance. Groups with certain
shapes are mathematically, provably, totally, dead beyond hope, assuming
proper play. At that time, many programs were weak in that area. Now, strong
programs usually do not fall into such simple traps.

 

In addition to "dead beyond hope" and "certainly alive", strong humans also
recognize "can live with ko" and "seki" shapes - again, beyond a shadow of a
doubt, as mathematically certain as the sunrise in the morning. 

 

The analogy with the stock market misses the mark because the stock market
has many millions of independent actors ( the human beings who make buy and
sell decisions ) who act upon many billions of facts, most of which are
inaccessible to the punditocracy who try to make sense of the markets.
(would-be pundits are also often handicapped by inferior models, but that's
another tale.)

 

Go is a game of complete information played by exactly two players, if we
ignore rengo or phantom variants; when the position is simplified enough (
something which strong players actively seek ), the result is mathematically
provable - and well within the limits of what humans can do with their
pattern recognition facilities. 

 

The topic here is that of large semeai; many games have shown that programs
are vulnerable to misjudging the outcome; Darren Cook has written up a page
describing the problem with random playouts and complex semeai which depend
upon precise move ordering. In many cases, semeai are won or lost by a
single play, and one must play A, B, C, D precisely in order, in response to
any one of Z, Y, W, X, etc. A large class of problems depend on "if my group
A loses a liberty, I must take a liberty from group B in such-and-such
order." Strong humans read out these problems and play them correctly.
Strong programs have been observed to fail.

 

Many well-known joseki create a local situation with such "win by 1"
capturing races. Usually, the person who loses the local race gains
something - "influence" or "thickness" in compensation; strong professional
players consider these sequences to lead to equal results for both players.
If a player takes that compensation, converts it to cash ( territory ), and
also manages to swindle a program out of winning the local semeai, the
player can easily win; it's like being able to write off a $500,000 mortgage
and keep the house, because the lender made a mistake in the paperwork.

 

It used to be fairly easy to set up a ladder and a ladder-breaker, and
programs would still play out the ladder as if the ladder breaker were not
present - a huge misconception. Strong programs don't seem to fall into that
trap anymore - but they do fall for semeai which are conceptually similar,
in a mathematically provable sense.

 

While I present a single game to illustrate my case, I generalize from many
games. It's still merely a black box analysis, however; I leave it to the
programmers to "open the box" and discover how the internals map to the
observable externals. 

 

There is a difference between Go and Chess. In Chess, only one thing
matters: put the other guy in checkmate, and you win, even if all you have
on the board is one king and one pawn, and the other player has a dozen
pieces. In Go, once you achieve a territorial advantage, you need only keep
what is yours. Going back a year or two, programs were not very good at
keeping what was theirs; they played odd yose moves which yielded up
territory without gaining anything in terms of improving their winrate.
Semeai are the midgame equivalent - moves which are mathematically
constrained in ways which significantly alter the real status of the game,
as opposed to the hypothetical winrate of any algorithm which does not
understand those constraints. 

 

Terry McIntyre <terrymcintyre at yahoo.com>

Unix/Linux Systems Administration
Taking time to do it right saves having to do it twice.

 

 

  _____  

From: Don Dailey <dailey.don at gmail.com>
To: computer-go at dvandva.org
Sent: Sat, November 13, 2010 10:14:03 AM
Subject: Re: [Computer-go] ManyFaces swindled of victory?




On Sat, Nov 13, 2010 at 9:08 AM, terry mcintyre <terrymcintyre at yahoo.com>
wrote:

Don, I'm enough of a go player to know that, in such a position, a 2d human
would trounce the kyu player, if given the middle game position to start
with - but I'd appreciate the views of a dan-level player.  MFGO in such
positions often fails to take care of its groups - even though it is far
stronger than I.

 

I'm not saying you are wrong,  I'm just trying to keep everyone honest.
It's just that the hair on the back of my neck sticks up when I see an idea
start to become gospel and I hope that as we figure all of this out we are
not making incorrect assumptions that will set us back.     

 

Here is what bothers me about this:

 

You saw a position and said, "in such a position" a 2d human would trounce
the kyu player.  Not only are you making a judgement about a specific
position (which may or may not be true),  but you are generalizing it based
on what you subjectively think "such a position" means.     You have used at
least 2 subjective opinions, linked them together and use this to draw a
conclusion.   (Presumably this is just a tentative conclusion,  a
hypothesis, which I think is the right way to think about such things.)    

 

Don't forget that as humans we have very strong pattern recognition
facilities.   We can see animals and all kinds of various objects in cloud
formations and studies have shown that we tend to find patterns in random
things.   This often tends to make us draw conclusions very quickly based on
little evidence or just plain gut feelings as witnessed by the large number
of criminal cases that were incorrectly judged.      This is both a strength
and a weakness that we have but it is the source of massive amounts of
incorrect "common wisdom."

 

How many times have programmers here observed something wrong with the way
their program plays,  made a judgement about WHY the program is playing
badly, and then implemented a fix which clearly addresses the problem they
think they are seeing - and lo and behold the program is now weaker?     It
was worth a try but it's way too easy for such a chain of reasoning to be
wrong.   

 

If you really want to see my point in action,  watch the stock market and
the way each days activity is explained at the end of the day.    They will
say something like,  "The nasdaq today was down based on fears of
recession."     The stock market is incredibly complex,  and yet the
analysts ALWAYS seem to know the exact explanation for why it went up or
down some slight amount.     And that explanation is presented as a
statement of fact,  the reason why.  

 

Sorry I'm being so picky about this but it drives me crazy, it's one of my
peeves.   You didn't do anything wrong :-)

 

Don

 

  

 

 

 

 

 

 

 

 

 

Dave Fotland himself has observed similar results; there are many game
records to back up this contention. A while back, I posted about a player
who has a very high winrate against MFGO - it looked like his account did
nothing else but play computer programs. 

 

Strong humans organize and prioritize things differently than (current)
strong programs.

 

If you can keep track of things at blitz speed, and set up complicated
fights with large unsettled groups, and patiently encroach on a program's
eyespace ( even DDK players know that a dragon, however large, still
requires two eyes to live ), you can often give a program a good drubbing.
 

Earlier, we had a post regarding a shogi program which combines the votes of
four other programs. 

 

Given that processor cores are now abundant, and that UCT programs have
trouble using all that horsepower, I wonder if some cores should look at the
board in an entirely different way and, every now and then, generate "Danger
,Will Robinson" signals which trump the usual winrate algorithms - or at
least tweak them toward safety moves. 

 

Is there a way to combine such disparate information into a coherent picture
of the board? 

 

Terry McIntyre <terrymcintyre at yahoo.com>

Unix/Linux Systems Administration
Taking time to do it right saves having to do it twice.

 

 


  _____  


From: Don Dailey <dailey.don at gmail.com>
To: computer-go at dvandva.org
Sent: Sat, November 13, 2010 8:18:19 AM
Subject: Re: [Computer-go] ManyFaces swindled of victory?





On Fri, Nov 12, 2010 at 9:24 PM, terry mcintyre <terrymcintyre at yahoo.com>
wrote:

This is a curious game - a 3 stone game betwixt ManyFaces and a 2 kyu
player. 

 

It looks to my eye as if MFGO was well ahead in the middle game, yet managed
to snatch defeat from the jaws of victory. 

 

Black has many unsettled groups; usually a stronger player causes much grief
in situations like this, but black managed to turn around and swallow up not
one but several white groups. 

 

Most interesting. I think this confirms an earlier thread - when there are
several semeai on the board, MCT-based strategies get into difficulties. 

 

Are you sure of this?    I think it is human nature to try to make sense of
things and create general rules and principles to explain what we think we
may be observing.   It's also human nature to often be wrong about it.
The first time an idea is skillfully presented it tends to carry extra
(sometimes undeserved) weight because everyone else interprets what they see
in terms of that and it gets repeated over and over till it becomes the
de-facto sound bite that propagates itself.  

 

Maybe it's completely true and there is no dispute or it's obvious -
unfortunately I'm not a go player so I'm in no position to add my 2 cents
but I would be very cautious about making  general statements about the
relative strengths and weaknesses of humans compared to computers.      

 

I know from experience with chess for many decades that peoples perception
of the computers strengths and weaknesses were constantly misinterpreted,
very often based on a just a game or two someone played.     People were
just trying to make sense of it, but they got it wrong a lot.    In one case
in the 80's my program played a master and lost tactically and believe it or
not the master felt the program was strong positionally but weak tactically
(because he beat it with a tactical shot) even though we now understand it's
completely the opposite.    The truth of the matter was that the computer
was simply a lot weaker than this particular player so it was inferior all
the way around.  

 

If your supposition is true, then it's a good thing to know because perhaps
it can be addressed.    Or it might end up being one of those things that
diminishes in importance over time as computers get generally stronger and
stronger.    In chess, computers have always been weaker in true positional
understanding (even to this day) but we have added so many layers of
strength that this weakness is only a relative thing.   It's weaker than
other parts of it's game,  but not so weak that anyone can easily take
advantage of it.   Most computer games resemble Grandmaster games in the
quality of positional play.

 

 

 

 

 

I think strong human players tend to have a better grasp of "this particular
fight is settled, no need to study it further until a liberty is removed (in
which case respond now!); let's focus on this other fight instead . . ."

 

 

 


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