Huh? Six tempo? Two, by my count, And, Dr. Tarrasch taught us you need 3 tempi to justify sacrificing one pawn. :-)

At move 9 my SF10 plays like SF8 did in this match, and its top line runs 9....fe 10.Nxe5 Nxe5 11.de Qxe5 12.Re1 Qc7 13.Bh5+ Ng6 14.g4 Bd3 15.Nf3(?), with a 0.00 evaluation at 41 ply.

At 19 ...Re8 it looks like the CG computer says .00 but blacks a pawn up so the position is closer to 1.00. Pretty bad if not lost probably. I'd think it would be hard to find many who would want black at that point.

Pretty bad or busted by move 20 doesn't seem that impressive.

White gains two tempi between Black’s 9th move and White’s 13th — the rook goes to e1 and it’s white’s move instead of black’s. Neither side gains any tempi after that, unless you count pawn moves, which neither Tarrasch nor I would do, particularly when they are moves like b2-b3 and g2-g4!?.

A0 launches its gambit with the modest 9.c2-c3, definitely not a tempo gainer, and the key move in the game is 19.Bf4-g3, a clear loss of tempo.

Again, huh? The computer says 0.00 (so does my SF10), but Black’s up a pawn, so it’s “really” +1 for White? I’m sorry, do pawns not count for you?

Computer evaluations are much more than just counting material. Considerations such as pawn structure, development, king safety, space and square control, threats, and many more are taking into account, suitably weighted as to their relative importance. So it's very possible that the computer evaluation of positional factors can be enough to compensate for any material disadvantage, and it's obvious that a forced mate in one with that player to move is enough to compensate for any positional disadvantage.

If the eval is 0.0 a pawn up then it would only make sense that if one drops the pawn with no compensation then the eval would likely be worse for the former holder of that pawn. If you drop the pawn with no comp and are also still positionally weak the eval probably goes against you pretty good.

This happens a couple of times in this game. SF ends up material and after awhile that material is gone and the eval just gets worse and worse. After 43..bxa6, isn't SF up two pawns but it doesn't take long for the eval to really turn against him.

This scenario plays out not just in this game but others as well. I just get the feeling, that for whatever reason these SF games feel more like 1998 computer chess than 2018 computer chess.

In this match SF seems to take material, even material that might be helpful or material that seriously weakens his position. Then the eval looks equal because the extra material counts as something but really is positionally very bad with no counterplay. So it starts out 0.0, then goes like +.33 then close to 1.0. All without SF seemingly being in the game.

Striking is the difference in counterplay A0 got in the same opening game referenced above.

At 42...Nb7, SF as black is 2 pawns up. CG eval is 0.0. At 50...c4, eval at +.50. At 55...Rf6 eval at +1.47.

White could have won the queen at move 19 and gotten a negative evaluation (19.Ne6 Nxf4! 20.Nxc7 Kxc7) or regained the pawn (19.Bxg6 hg 20.Bxe5 Qd7) with a 0.30 evaluation from my SF at 40 ply. So it's not like the 0.00 evaluation after 19....Re8 (which my SF maintains after an hour, incidentally) is secretly terrible for Black but masked by an extra pawn.

<SChesshevsky: Related to my last post, here's an interesting example where SF as black is 3 pawns up at 32...Bd7 and the CG computer has the eval at +1.07.>

Seriously, SChesshevsky? Here's the position, white to move.

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A modern engine, a 1998 engine, and your average club player could tell that Black has got serious problems. Do you think SF8 was thrilled with how things had gone? I'm sure its evaluation was at least as bad as my SF10's evaluation's is. You seem to think SF8 <wanted> positions like this. No one and no thing does!

At that point SF had been at least two pawns up for 16 moves. It had refused a third pawn at move 18 (which it probably should have taken, incidentally). It had taken a pawn at move 27 and then immediately given it back. It had no decent alternative to taking a third pawn at move 30 -- judge for yourself. It was offered a fourth pawn on move 32, which it refused. And it had been hit with a whole series of remarkable moves by its opponent.

You seem to think SF sleepwalked through these games picking up every pawn on offer. That's not what happened.

(Incidentally, my SF10 evaluates the position at move 16 (when it's two pawns up) at 0.00 at 41 ply. It plays the opening exactly the same way SF8 did in the match.)

<SChesshevsky: Hey, another one: At 42...Nb7, SF as black is 2 pawns up. CG eval is 0.0. At 50...c4, eval at +.50. At 55...Rf6 eval at +1.47.>

This is just more of the same. Here's the position at move 42.

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I'm surprised the cg website evaluation is only 0.00, frankly. My SF eval is +0.32 at 39 ply. The position at move 50 is similar. And I hope you noticed that at move 55 SF is the exchange down, with more material about to go.

In that game, SF had been a pawn up since move 4 (not by its choice, obviously) and had taken a second pawn on move 41, by which time its position was already looking questionable to this patzer, and would have remained questionable whether the pawn was taken or not. So whatever got SF into trouble in this game, it wasn't blind greed.

Finally, you're drawing conclusions from an unrepresentative sample of games. SF and A0 played 1000 games without opening books. (I don't know the exact breakdown for the other games, except that SF was more likely to win games played with pre-set openings.) A0 won 155 games, SF won six, and the rest were drawn -- nearly 85% of the total. So obviously games in which SF went way up in material but wound up losing were exceptions, even if all A0's wins were like the game in the first diagram above, which is not the case.

One other point about this game. As I noted earlier, I'd be very happy to play Black at move 19, if I didn't know better from experience. If you told me I was going to lose, and asked me to guess how it would come about, you know what I definitely <wouldn't> predict? A double-rook-and-opposite-color bishop ending where I had an extra pawn. That (along with 14.g4, and the sustained anticlerical campaign) is what blows my mind about this game.

One more for you.

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Black's a piece up, but horribly undeveloped and obviously going down in flames. In fact it resigned here.

My take is that it's tough to tell how good as it's SF that is playing sub optimally. In my opinion.

You mentioned at some point SF didn't want a certain position but that's what it went for. And in those circumstances the lines didn't seem forced. In this game it was SF who set the p!ay with taking the pawn ending ...Qxe5.

So the analysis really doesn't have anything to do with A0 but where SF went wrong and what if any are the improvements. I think it was the e5 grab idea or if that line is best then back at ...f6 that wasn't good.

If we're talking about the position after move 32 in AlphaZero vs Stockfish, 2018, I don't think it makes sense to talk in terms of SF <going for> that position, any more than A0 <went for> that position I posted from its blowout loss to SF. Or I <go for> the terrible positions I generally wind up in against stronger opponents.

<So where did SF go wrong [in this game] and are there any improvements?>

Putting aside 8....f6, which seems to be dubious, SF's clearest error seems to be 20....Kb8 (+0.67 at 40 ply) instead of ...Qd8 (+0.19 at 41 ply) or ...Bd6. In qualitative terms, 20....Kb8 seems to give A0 a more or less straight path to the favorable ending arising at move 28, where Black's weak back rank is one of White's biggest assets.

Later on, SF might have given back the pawn with ...d5-d4, giving its bishop a more secure perch (Daniel King's suggestion). And it should have played ...a7-a6 at some point rather than just sitting tight and sliding its rook back and forth between d8 and c8.

In human terms, taking the pawn at move 9 was risky, but probably objectively best. I have no doubt 9....fxe5 would get the best engine evaluation for Black at any reasonable search depth.

I let my SF10 run at move 9. After the first few seconds, its top choice is unvaryingly 9....fxe5. At 10 minutes/40 ply, its evaluation is +0.13, i.e. it thinks White is slightly better. It's certainly not thinking, "Hey! Free pawn!"

Its line runs 9....fxe5 10.Nxe5 Nxe5 11.dxe5 Qxe5 12.Re1 Qc7 13.Qb3 e5 14.Nf3 Be4 15.Rad1. It hasn't seen (or isn't impressed by) the Bh5+/g2-g4 idea.

At 42 ply/16 minutes, the eval has risen to +0.44, but it's still playing 13.Qb3 e5 14.Nf3 Be4 15.Rad1.

At 43 ply/27 minutes, the eval is +0.45 and the line is 13.Qb3 c5 14.Qb5+ Nc6 15.Bxc5.

I agree that A0 13.Bh5+ is very good but certainly seems logical. Gains a tempo and forces some sort of weakness. I wonder why your SF is not impressed? Maybe black eventual ...c5 freeing move which can be something looked for in CK advanced?

I don't know either. But consider that if the evaluation was [0.01] less (an insignificant amount) then it would be subjectively assessed as "White stands definitely better". Would that change your guess?

Don't get me wrong, guesses are fine. But unless you're a top-level GM (and even then), they would still be just guesses although in the latter case they would be educated guesses. But still guesses. I just prefer to have some data to back up whatever conclusion I "guess" at.

<After 43..bxa6, isn't SF up two pawns but it doesn't take long for the eval to really turn against him.>

That's what evals often do in complex positions, particularly if the engine generating the evaluations is subject to the horizon effect; they can swing widely. Remember that AlphaZero's evaluations are based on simulated games conducted to the end and a statistical assessment of the results. So, I don't think, AlphaZero is subject to the horizon effect, at least not as much as "classical" engines like Stockfish. And, running on much more powerful hardware, it can get more accurate assessment of the most likely results of each move.

<I just find it strange that a standard top 2018 engine would frequently get itself into such passive positions when it's opponent plays generally just natural moves.>

Hi K.P.

This game is on page 268 of 'Game Changer' (I'm doing as the book suggests, jump about a bit, no need to read it in order.)

We get to here:

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Alpha starts the wood chopping to get to here.

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Mathew Turner writes: (I'll paraphrase.)

Alpha's plan is simple.

Double Rooks on the e-file and due to the back rank mate threats this will keep the Black Rooks tied down.

Get a Rook on the 7th and if given the chance double the Rooks on the seventh.

The White DSB keeps the Black King out of the game whilst the White King becomes very active on the Kingside. (look how the game went for more clues.)

Mathew reckons Black cannot do anything to prevent this and has played two engines from this position as White and won.

(Not tried it yet but I will.... I just know I'll screw it up. I'll play it v Fritz 6 level 2. I always win those. )

It appears Alpha saw this position coming liked the activity and the fact Black is passive. S.F. allowed it to happen guided by the fact it was a pawn up.

Maybe Alpha has just highlighted a S.F. weakness. S.F. will let you have all the activity you want provided you give it material and it cannot (yet) see any way you will be winning it back.

Alpha uses it's activity (and every two move trick in the book) to deny any counter play then sets about forcing a weakness to exploit. Sounds easy but very hard to do. This is Capablanca masterpiece while he still had the gift territory, without the pawn sac(s) to grab/steal the activity.

---

Playing through it I've scribbled in the book here.

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'Why not 54.c4 '

(it blocks the defence by the Bishop of the a6 pawn. if Black takes it Be5+ and Ra1. 1-0.) Alpha played 54.f4.

<S.F. allowed it to happen guided by the fact it was a pawn up.

Maybe Alpha has just highlighted a S.F. weakness. S.F. will let you have all the activity you want provided you give it material and it cannot (yet) see any way you will be winning it back.>

I tend to be rather defensive about SF's abilities, since "stupid iron monster"-theme comments like the foregoing tend to diminish A0's accomplishment. As you can see by scrolling down, SChesshevsky and I had quite a back and forth about how SF evaluated/handled the position.

I guess there are two things I'd say:

-once the endgame was reached, there weren't a lot of ways (that I saw) that SF could have tried to get activity. It could have given up the d-pawn to give its bishop another diagonal, but I'm not sure that would have really helped (one of A0's ideas was to sac the exchange on g6 and win the resulting ending). Or it could have played ...a7-a6 instead of waiting for a5-a6 from its opponent. But that's not very active.

-SF, or at least my SF10 running on my desktop, was <never> very happy with Black's position (remember, the opening was assigned, the machines didn't choose it). I have several posts about that on this page.

At move 9, in a deep search, SF10 thinks taking the pawn is Black's best option but evaluates the resulting position as better for White.

At shallower depths thereafter, the eval is generally somewhere between 0.00 and slightly positive (i.e., slightly better for White).

Hi K.P.

As you have S.F. and I do not I'll go along with you.

Mathew does a section on the 0.00 evaluation which I ma currently reading.

Since Alpha it appears we know a bit more about how the the other computers 'thought.'.

Go and look at G Chandler vs V Slaven, 1991

I'm ahead of my time, I did everything Alpha does.

Sacced a pawn in the opening.

played h4 after 0-0 (saccing another pawn) to make a move on the Queenside.

Rook lift a1-a3-h3.

Played g3 and Kg2 to get the other Rook to the h-file - Alpha does that. AlphaZero vs Stockfish, 2018

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18.Kh2 19.Rh1 20.Kg1.

You can why I'm liking what I am seeing. (stick it in with Alpha games - this should be in the book - have to get this game to Sadler!)