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Duchess (Computer) vs Kaissa (Computer)
World Computer Championship (1977), Toronto CAN
Scandinavian Defense: Richter Variation (B01)  ·  1-0



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Kibitzer's Corner
Jun-06-05  korger: This game could have created a mild sensation at the time it was played. Black's seemingly suicidal and nonsensical rook sacrifice 34. ... Re8?! baffled human spectators, and even Kaissa's designers considered it as an error in the yet experimental computer. But after the match was over, a consultation with Kaissa revealed the reason for this "blunder": the obvious 34. ... Kg7 would have been countered by a neat queen sacrifice: 35. Qf8+! Kxf8 36. Bh6+ Bg7 37. Rc8+ and White gives a mate in two moves! Very simple for today's computers, but a great achievement in 1977. Well, computers have always been great at combinations...

This was my first Kibitz for How can we cite messages posted earlier, and make references to other games?

Jun-06-05  Shams: <korger> 35.Qf8+! is a great shot.

there's a kibitzing tricks page that I can't find right now. basically, just cut and paste URLs and if it's from this site, it will show up as the match name instead of just the url string.

and use <angle brackets> for different colored quotes. <you can even <nest> if you like.>

Premium Chessgames Member
  alexmagnus: Ah, this game is kind of a milestone in computer chess and also the most curious moment in comp chess history: when Kaissa playes that Re8 move, no commentator even tried to see why it could be best - they just said something along the lines: "well, computers are still not good...". Kaissa's response to Kg7 in post-mortem was a shock to everyone watching.
Jul-14-14  Sally Simpson: As the above poster stated 4 years ago... It is one of the milestones in computer chess history.

Here Black to play it's 34th move.

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It played the silly looking 34...Re8.

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According to CHESS Octobr 1977 the players watching this game included Botvinnik, Ed Lasker, Hans Berliner and the Canadian IM Leon Piasetski.

All of them missed the reason why.

Back here.

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If Black plays 34...Kg7 then 35.Qf8+!

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And mates! The longest variation being

35....Kxf8 36. Bh6+ Bg7 37. Rc8+ Qd8 38. Rxd8+ Re8 39. Rxe8.

click for larger view

The real tragedy being if Black had played 34...Kg7 Duchess (White) would not have seen 35.Qf8+. At 9 ply it was too deep for it to see.

For example Duchess failed to 'find' 37.Rc8 here

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Which simply wins another piece.

So back on move 34 Kaissa chucked a Rook because it could see deeper than it's computer opponent and two human ex World Champions. Botvinnik OTB and Berliner in Correspondence Chess.

Sometimes the best move is not the best move to play.

Jul-14-14  team kids can win: <30 - White to play and win> is a pretty cool puzzle in this game, and it's interesting that <Sally Simpson>'s commentary about Duchess only seeing 9-ply deep implies that Duchess solved that puzzle without actually understanding it was a winning move. <30.g4> forces <30...Qe6> because it's the only escape square for the Black Q. <31.Rc6 attacks that square>, forcing <31..Rd6> or the pointless, low-play mirage variation played by Kaissa with <31..a4 32.Qxa4>. <32.Rxd6 Qxd6 33.Rc8+ Kg7 34.Rc6 Qd8 35.g5> traps the Black Bishop after <35..Bxg5>. So,counting <30.g4 Qe6 31.Rc6 Rd6 32.Rxd6 Qxd6 33.Rc8+ Kg7 34.Rc6 Qd8 35.g5 Bxg5 36.Bxg5> is over the 9 ply horizon.
Jul-15-14  Sally Simpson: Hi TKCW,

I should have made it clear. The article said 9 ply was beyond Duchess. It was not me trying to figure out why it was missed.

B.H. Wood adds a comment in the article that many human players would have missed the 35.Qf8+ idea. (indeed given the company that apparently witnessed it, this sounds plausible.)

From a set position on a puzzle page I think a lot would get it. But if it cropped up in a game then I can see it easily getting missed.

Sep-05-15  konstantin71: According my computer Kaissa did 1st mistake here:
29... a5? instead of any attacking move on King side
31... a4? and 32... Rd6?? were blunders
Oct-08-15  Sally Simpson: I've submitted my first pun.

"The Frankenstein Monster Awakes."

It was this game when a computer playing a move (34...Re8.) that had the strong players present baffled and programmers stripping down the machine to see what was wrong.

Premium Chessgames Member
  AylerKupp: <<Sally Simpson> The real tragedy being if Black had played 34...Kg7 Duchess (White) would not have seen 35.Qf8+. At 9 ply it was too deep for it to see.>

Even if what the article said was true, that 9 ply was beyond Duchess, that probably meant that <on the average> 9 ply was beyond Duchess. But by this time the concept of search <extensions> was well known; Shannon in his classic 1949 paper described his Type-B strategy involving what came to be called <quiescent positions>:

"From these remarks it appears that to improve the speed and strength of play the machine must:

(1) Examine forceful variations out as far as possible and evaluate only at reasonable positions, where some quasi-stability has been established.

(2) Select the variations to be explored by some process so that the machine does not waste its time in totally pointless variations."

He further indicated that "It is not difficult to construct programs incorporating these features" and even described how it could be done.

Duchess was a strong engine at the time, playing in 7 ACM North American Computer Chess Championships from 1974 to 1981. It also finished 2nd in the Second World Computer Chess Championship and tied for first in the Eighth North American Computer Chess Championship, both in 1977. So it was likely that in 1977 it incorporated the concept of quiescent search, particularly since it also incorporated the concept of iterative search deepening. See https://chessprogramming.wikispaces.... The clincher as to whether the Duchess programmers were familiar with Shannon's concepts is a photo on the page indicated by the link of Claude Shannon himself sitting on the side of Duchess in the game Duchess vs. Belle, although the photo is dated 1980 (and Duchess lost that particular game).

The longest sequence, as you pointed out, is 34.Qa8+ Kg7 35.Qf8+ Kxf8 36.Bh6+ Bg7 37.Rc8+ Qd8 38.Rxd8+ Re8 39.Rxe8#; 11 plies. But this includes at least 2 captures, 35...Kxf8, 38.Rxd8+ and possibly 3 (39.Rxe8#) depending on how Duchess counted captures. And if Duchess also incorporated forced moves into its quiescent search categorization (per Shannon), then that also includes 37...Qd8 and 38...Re8. So that's at least 4 plies out of 11 when Duchess would nave needed to evaluate only 1 or 2 positions per ply, reducing the number of nodes to be evaluated signifcantly. Given that Duchess was able to evaluate about 200,000 nodes in its search tree per 3-minute move (same wikispaces link), it seems to me that Duchess was quite capable of identifying that 11-ply Principal Variation even without search tree pruning heuristics, given that alpha-beta pruning was probably also used, since that principle has been known since 1956 (, particularly since it would have an overwhelming material advantage (up a queen) by the 9th ply after 38.Rxd8+ so it would have been predisposed to select this line as its PV. And we certainly know that Kaissa was able to do that since the horizon effect kicked in and it played 34...Re8 to delay the inevitable mate as long as it could.

But, if Duchess was indeed unable to see the entire longest mating sequence after 33...Qxd6 due to its 9 search ply limit, then I can formulate AylerKupp's 2nd corollary to Murphy's Law (see my forum's user profile header for the first):

"If you use your engine to analyze a position to a search depth=N, your killer move (the move that leads to a forced win) will be found at search depth=N+1, regardless of the value you choose for N, and your engine will miss it."

Premium Chessgames Member
  AylerKupp: I think that the following quote by Monty Newborn (ICCA president from 1983 to 1986) in 1977 at the 2nd World Computer Chess Championship is appropriate to this game, and maybe inspired by it:

"In the past grandmasters came to our computer tournaments to laugh. Today they come to watch. Soon they will come to learn."

This game would certainly be the start of phase 2 in the quote above.

Oct-09-15  Sally Simpson: Hi Aylkerkupp,

I can remember the buzz it started.

It was the second landmark after MacHack/Greenblatt beat a human in 1967.

In August 1968 Bobby Fischer called this game 'a disgrace to the human race' and states that yes a chess computer will become a champion but hopes not in his lifetime. (not a bad punt, Deep Blue beat Kasparov 30 years later.)

I know chess programs talk to each on the inter-net, they have their own site somewhere.

Here we drool and throw exclaims !!! at the Morphy at the Opera game. Computers whoop with delight when this game is mentioned and you can understand why when you see the final position from the Greenblatt - Landey game.

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Greenblatt vs B Landey, 1967

compare to the final position from the Morphy game.

click for larger view

Oct-09-15  psmith: I was present at this game (in Toronto)! iirc, after the tournament one of the programs played two blitz games with IM Lawrence Day, losing one and winning the other. (Probably the tournament champion Chess 4.6, but I am not sure.)

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