Questioning the analysis

I gather this is SF analysis available here on my daily game

https://www.chess.com/analysis/game/daily/253862254

but when he resigned, I did seem to be winning ( -1.09 ) and so to see what would / could have happened, I followed all of the "best" moves, which led to a perpetual check for white.

So I found a way to get past that / get out of that with one move that kept it at 0.00, and it stayed 0.00 for ages, and then I kept doing the best moves all the way, and it led straight to this

which clearly states that white is winning now.

winning by +1.07.

So,....., why isn't the analysis working out? How can I have been ahead when he resigned, if SF can't make it work out?

Really confusing

ahHAH. If anyone is bored perhaps they could do that, I am not sure how to start...

It's a draw, according to the Syzygy 7-man tablebase.

hmmph.

I wonder if it were a draw when it was telling me I was winning, right when he resigned.

Thanks very much for looking at it @blueemu, sounds like you might have done me a solid there : )

This is the tool I used, by the way:

https://syzygy-tables.info/

Right on, thanks very much for the link. I assume it would be very important to never have that open when you are playing on this site.

Correct. Table-bases are not allowed even in Daily games (which do allow some other types of resources).

Thanks for the link to the table-base.

From that page:  "From May to August 2018 Bojun Guo generated 7-piece tables. The 7-piece tablebase contains 423,836,835,667,331 unique legal positions in about 18 Terabytes."

Yet it very quickly told me that wollyhood is winning from the diagram of the OP.  Amazing.

Are you sure you entered the position correctly? The White King is on c3, not f6. It tells me that this is a draw.

hm

now that I look back at the finish of the game, I see that I made the best last two moves possible (according to the analysis) and yet, my probability of winning went down (from -1.38 to -1.08) after those two turns.

I am seriously confused now.

How can my winning advantage whatever it is go down so much, when I made the best moves???

You can also download the Lomonosov tablebases app on your smartphone. It tells you in exactly how moves each move wins/loses or if it's a draw.

Also @litedave that is concerning, because if a different analysis says that I was winning as per the OP, but only drawing at the end then surely either:

both engines are being silly, OR

the analysis here is not correct?

Horizon effect.

The table-base is analyzed right out to mate or draw, but the chess.com analysis is only a set number of half-moves deep.

Let's say 20 half-moves.

Once a move is actually made on the board, it is removed from the analysis queue and the analysis is extended one move deeper, to again reach 20 (or whatever) half-moves deep.

In effect, the new position only "comes over the horizon" after you make a move on the board.

So the evaluation can change every move even if you are making the "best" move.

Hm, but the syzygy one also said I start off winning and then end as a draw? But I guess that is based on chess.com "best" moves as I tried to follow them pretty exactly ....

I am just finding it hard to trust the analysis if it is so changeable, even with the best moves. Is that the lesson? Don't trust the analysis too much? Play more positionally?

Winning at what point? The only position I entered was the one pictured in your OP.

Thanks, I think I will keep chess software off my phone for now xD

Am even nervous I have the syzygy window open when I was looking at our vote chess but luckily I didn't have any analysis happening apart from the one I made earlier.

ohhhhhhh that is good. I misread you earlier and thought you said the end position was a draw.

constancy.

Yes, the end position is a draw. According to Syzygy 7-man table.

In which position were you told you had a win?

That final position was the only one I checked.

It (chess.com analysis / report) says that @ 20...bxe3 I am up as black -1.38, then they make the best move and take me, and then I make the best move at 21...f5 and I am still winning but only at -1.08

https://www.chess.com/analysis/game/daily/253862254

Yes, that's the horizon effect described above. The chess.com analysis only goes a certain number of half-moves deep and then the position is evaluated. So when you make a move on the board, that move is cleared from the analysis queue, the analysis extends one move deeper, and a new position is evaluated (often, changing the value).