[HN Gopher] How to Calculate the Trappiest Openings in Chess Usi...
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       How to Calculate the Trappiest Openings in Chess Using Stats
        
       Author : datashrimp
       Score  : 77 points
       Date   : 2021-10-16 11:01 UTC (1 days ago)
        
 (HTM) web link (medium.com)
 (TXT) w3m dump (medium.com)
        
       | seanhunter wrote:
       | I absolutely would have guessed Stafford as the top with Englund
       | near so the resulting ranking seems to correspond strongly with
       | my intuition at least. I'm surprised Blackmar-Diemer is so high
       | but maybe that becomes more viscious when you're higher rated
       | than I am.
        
         | datashrimp wrote:
         | That's good to hear! Blackmar-Diemer is favoured by this
         | ranking system as although it's a longish line, the opponent's
         | move are all fairly probable, with the least probable being
         | Qxd4 at still around 20%.
        
       | eddd wrote:
       | Eric Rosen porn.
        
       | perpetualpatzer wrote:
       | I imagine the answer here varies a lot by elo of the training
       | corpus because skill effects the probability input. In the 500s,
       | 3. Qh5 to scholar's mate is both potent and very probable. In the
       | 1300s it's just a mistake. It would be really interesting to see
       | the overlap between high and low elo traps.
        
         | datashrimp wrote:
         | Absolutely - in the repo, you can adjust for the skill of the
         | opponent https://github.com/davidADSP/chess-trap-scorer.
         | 
         | The analysis so far has been for 1600-1800 players.
        
       | Gehinnn wrote:
       | It would be nice to have a chess trainer AI that considers the
       | human factor when evaluating a position.
       | 
       | It's funny that it is relatively easy to beat stockfish when the
       | computer has to play without the queen. But it is quite hard to
       | beat a pro player even with such a strong handicap.
       | 
       | Still, the pro player has absolutely no chance against the engine
       | without an handicap.
       | 
       | Assuming that stockfish runs on a computer that is _much_ faster
       | than what we have today and sees that white can always forcibly
       | win, I wonder if stockfish would immediately resign as black
       | playing against a human, even before the very first move.
        
         | captn3m0 wrote:
         | maiachess.com is "A human-like neural network chess engine"
         | which is trained at 9 skill levels (1100-1900).
         | 
         | >We tested each Maia on 9 sets of 500,000 positions that arose
         | in real human games, one for each rating level between 1100 and
         | 1900. Every Maia made a prediction for every position, and we
         | measured its resulting move-matching accuracy on each set.
         | 
         | >Each Maia captures human style at its targeted skill level.
         | Lower Maias best predict moves played by lower-rated players,
         | whereas higher Maias predict moves made by higher-rated
         | players.
         | 
         | Previously on HN: https://news.ycombinator.com/item?id=25810034
        
         | momothereal wrote:
         | In sufficiently advanced CPU vs. CPU, the Black side would
         | definitely resign on the first move.
         | 
         | However, assuming White has a 10% higher chance of winning in
         | games between 2 Human players, that still leaves a decent
         | margin of error for the White Human side to blunder during the
         | game, so Black CPU wouldn't resign. This is assuming CPU
         | doesn't know about that individual Human's blunder history.
         | 
         | Basically, CPUvCPU would definitely see an instant resign. In
         | HUMvCPU, only the Human should definitely surrender as black. A
         | Black CPU will keep playing in case the Human blunders.
        
           | nuclearnice1 wrote:
           | > Black side would definitely resign on the first move.
           | 
           | Glancing at Wikipedia https://en.m.wikipedia.org/wiki/First-
           | move_advantage_in_ches...
           | 
           | This claim seems ahead of consensus? What evidence tells you
           | that black is lost at move 1 rather than drawn?
        
             | [deleted]
        
             | nullc wrote:
             | It was a thought experiment set by the ancestor post for
             | the purpose of discussion. "Assuming that [...] sees that
             | white can always forcibly win"
        
               | nuclearnice1 wrote:
               | Ah right I see
        
         | sam2426679 wrote:
         | > But it is quite hard to beat a pro player even with such a
         | strong handicap.
         | 
         | Don't take this the wrong way, but how good are you, i.e. what
         | is your rating?
         | 
         | imo, any reasonably seasoned player, after handicapping their
         | opponent to be without a queen, should be able to easily win in
         | a relatively straightforward by avoiding blunders and trading
         | off pieces.
        
           | YetAnotherNick wrote:
           | You underestimate the amount of traps a strong player could
           | have by making the position complex. Hikaru could beat >2000
           | rated player in queen odds[1].
           | 
           | [1]: https://www.youtube.com/watch?v=Fo8GOAm1E6c
        
             | pharrington wrote:
             | I wonder how different the results would be if the high
             | skilled players didn't know they were playing against
             | Hikaru.
        
               | eeegnu wrote:
               | Probably would be the same as playing against alpha zero
               | without knowing and wondering how every good move you
               | play seems to leave you worse off.
        
       | dmurray wrote:
       | > In order to compare lines of different lengths, we take the
       | geometric mean of the probabilities, to give the average
       | probability of the opponent playing the next required move in
       | sequence.
       | 
       | This doesn't seem right to me. A line where your opponent has to
       | find ten 75% moves in a row to fall into it is less "probable",
       | by any reasonable understanding of the word, than one where he
       | has a 50% chance of going wrong immediately.
       | 
       | I'd multiply the probabilities move by move to get the cumulative
       | probability, but I'd only start at the point where the trap-
       | setter plays a suboptimal move, to account for these different
       | lengths of lines.
        
         | datashrimp wrote:
         | The longer lines are technically less probable, like you say -
         | I was trying to capture the notion that a trap is more
         | impressive if on average, moves are likely. How would you
         | define 'sub-optimal' move in your proposal? It's a good idea
         | -would be interesting to see it in action!
        
           | dmurray wrote:
           | I can't think of a good way to do this purely based on move
           | stats: I think you'd want to involve the engine. There's a
           | Stockfish package for Python you could use, and it wouldn't
           | be expensive or difficult to query the few evaluations you'd
           | need. I would say a suboptimal move is when the evaluation
           | changes by more than X, maybe 50 or 80 centipawns.
           | 
           | I tried out the project and sent you a couple of minor pull
           | requests. I wanted to score my pet trap:
           | 
           | 1. e4 c6 2. Nf3 d5 3. d3 dxe4 4. Ng5 exd3 5. Bxd3
           | 
           | after which the most popular moves Nf6 (trap score 34%) and
           | h6 (trap score 29%) both lose immediately to Nxf7 (if Kxf7,
           | Bg6+ and Qxd8 wins the queen). I've seen plenty of titled
           | players fall for this. I think the correct way to score this
           | trap is the sum of those trap scores, because the "trap" is
           | set after Bd3, but there are multiple ways to fall into it.
           | That would give it by far the highest score at 63%, but maybe
           | changing the methodology this way would also increase the
           | score of your other traps.
        
       | lixtra wrote:
       | I miss: A good trap is safe - if the defender responds optimal,
       | the trap setter is not in a worse position than before.
        
         | tromp wrote:
         | The Stafford Gambit doesn't fare well there. It requires Black
         | to play 3. ... Nc6 in the Russian defense after 1. e4 e5 2. Nf3
         | Nf6 3. Nxe5 which according to Stockfish loses more than a
         | pawn's worth (eval +2 for white after Nxc6 d3 Bc5 h3).
         | 
         | The Noah's Ark Trap is much safer, as black only loses a
         | fraction of a pawn going into the line
         | (https://en.wikipedia.org/wiki/Ruy_Lopez,_Noah%27s_Ark_Trap ).
        
         | dmurray wrote:
         | In chess theory a "trap" normally means the opposite, a move
         | that is not optimal but gives the opponent a chance to go
         | wrong.
        
       | yewenjie wrote:
       | I would love to see an interactive version of the same that would
       | let me filter with rating ranges and time control.
        
         | datashrimp wrote:
         | I'll see what we can do!
        
       | _0ffh wrote:
       | It might also be interesting to calculate the win probabilities
       | for the players when the trap is avoided, so you can judge what
       | you pay for setting the trap.
        
         | datashrimp wrote:
         | Great idea!
        
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