[Computer-go] ManyFaces swindled of victory?

David Fotland fotland at smart-games.com
Thu Nov 25 23:49:21 PST 2010


At move 162 Many Faces also likes C7, with an 83% win rate.  There seems to
be a problem specific to Fuego in this position.

David

> -----Original Message-----
> From: computer-go-bounces at dvandva.org [mailto:computer-go-
> bounces at dvandva.org] On Behalf Of valkyria at phmp.se
> Sent: Thursday, November 25, 2010 11:24 PM
> To: computer-go at dvandva.org
> Subject: Re: [Computer-go] ManyFaces swindled of victory?
> 
> In the position at move 162 Valkyria would simply play C7 with a score of
> 80%.
> The eval of the position looks very straightforward to Valkyria.
> 
> My guess it that in this position Fuego as number of problems due to
> bugs perhaps in many patterns on the board that is specific to Fuego.
> Or that it later in the game evaluated some bad moves better than good
> moves ending up in positions very many local misevaluation lead to a
> global collapse. this is not the same as the semeai weakness. But is
> the same in the sense that tree search cannot resolve a position with
> many local tactical possibilities that is mishandled by the playouts.
> 
> Best
> Magnus
> 
> 
> Quoting dave.devos at planet.nl:
> 
> > I can only speak from one example from 2009 of me (4d EGF) playing
> > against a strong Monte Carlo program (Fuego) on 19x19, Fuego taking
> > 3 stones handicap.
> >
> > It was a game on a turn base site with one day per move thinking
> > time. Fuego was playing multiple games on that site and on 19x19 it
> > was allowed one hour thinking time per move per game if I remember
> > well. I usually don't use more than one or two minutes per move in
> > these conditions.
> > This is the game:
http://www.online-go.com/games/board.php?boardID=176261
> >
> > Up to move 107 things were going well for Fuego. I was quite
> > impressed be it strength. Then Fuego started a ruthless attack and
> > it was very succesful. By move 128 I was in big trouble. I despately
> >  tried to wriggle my way out of the situation, but by move 161
> > things  had turned even worse for me. I felt I should resign, but I
> > couldn't  bring myself to it. Then Fuego played 162. A totally
> > irrelevent  move, almost a pass, allowing me to play 163 to save my
> > group and  regain hope. And from then on Fuego played more
> > irrelevant,  incromprensible weak moves until its totally won
> > position had turned  into a lost position.
> >
> > I don't know if it has to do with semeais or multiple fights or
> > simply a bug. This game did not seem to have an exceptionally large
> > number of fights or semeais to me. I was surprised by the transition
> >  from consistently strong play to consistently weak play. From move
> > 162 it felt as if a was playing a different, much weaker player.
> >
> > I know Fuego is not Many Faces, but I read the same issue about
> > fights and semeais applying to all MC programs. Yet I felt that
> > semeais and fights were not the problem in this particular game. I
> > don't know what was. It felt like a general collapse.
> >
> > Dave
> >
> >
> > ________________________________
> >
> > Van: computer-go-bounces at dvandva.org namens David Fotland
> > Verzonden: za 13-11-2010 17:52
> > Aan: computer-go at dvandva.org
> > Onderwerp: Re: [Computer-go] ManyFaces swindled of victory?
> >
> >
> >
> > 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.
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> 
> 
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