How is that possible that on my computer i can keep it running long time and scan cant see win. And on phone it finds it immediately? Computer wants to go 50-44 with -0.4 score even after 30min on.

lidraughts.org/9LcqMTi7#28

611135

Probably it's using resources from your phone, and on a computer it works only in cloud.

Generally speaking, Scan tends to underestimate a win by imprisonment, except if it can rely on tablebase data.
However, your position is out of tablebases, so the engine can go wrong easily.
So far, I don't know a good draughts engine which recognizes a win by imprisonment on a horizon: for example, in this aspect Kingsrow International isn't much better than Scan.
I believe that an engine who relies on neural networks, could give more credible evaluations.

The question is. Why my computer with strong processor can't see it even after very long thinking. And on my phone can with bad processing power. It doesn't make sense

@dtmylens Check your PC settings, particularly with regards to CPU. If an access to CPU is limited or blocked (and some antivirus programs love to do it), of course, you will have these issues.

+ as well, you need to increase DEPTH of analysis by clicking on blue "+" sign. According to standard settings, it is 16, but you should be able to increase, and then more calculations are performed and the evaluation gets corrected.

@dtmylens nice question!

My guess is that you perhaps entered 15.2520 on your phone before letting it run? Engines tend to remember variations and that's how it spots the win seemingly right away.

I've been running the position on my laptop now for several minutes and it's getting to Depth 36/99 with 2265 knodes/s (showing 15.50-44 with -0.6 score)

While on my phone depth is 38 with 18085 knodes/s, but after 2.5 minutes it only gives 5044 with +0.1 score
With 38 ply you'd say that the imprisonment is within the horizon of the engine; however, I think the engine 'throws away' (ignores) a variation if it sees that it's 3 pieces behind with no immediate compensation for that

1

Wow good point. When I enter the game in the phone it's opening on the position after last move. So maybe scan remembered how the game actually finished or processed during those few seconds when I was reversing to key position.

When I put the position again from the opening phone failing as well. Interesting.

Thanks for explanation.

By the way, only few of draughts engines allow to run the retrograde analysis: good example is Aurora Borealis.

+ I included a similar example in my studies, and you can check how does evaluation work:
lidraughts.org/study/6KiWap9p