Tweak pawn connections

[locutus2]

Use less bonus for blocked connected pawns so closed positions are less worth.

STC:
LLR: 2.96 (-2.94,2.94) {-0.50,1.50}
Total: 60004 W: 11904 L: 11619 D: 36481
Ptnml(0-2): 1066, 7083, 13535, 7136, 1182
https://tests.stockfishchess.org/tests/view/5e941a8063d105aebbab23e3

LTC:
LLR: 2.95 (-2.94,2.94) {0.25,1.75}
Total: 36606 W: 4831 L: 4556 D: 27219
Ptnml(0-2): 252, 3353, 10872, 3520, 306
https://tests.stockfishchess.org/tests/view/5e9444b963d105aebbab2427

Bench: 4961260

[Rocky640]

For a supported white pawn on e5 against a supported black pawn on e6, (a french structure)
this is a White penalty of S(11,7) compared to current master.

This result is rather unexpected

[locutus2]

@Rocky640
Yes. In general this should disencourage closed positions.

[locutus2]

This penalty have a broad effect.

Most important is to avoid the lockdown in the center if it not berings you an advantage,
Perhaps only counting center pawns is better.

Further i recently tried something similiar where only connected pawns which directs not to the center was a penalty given. I should try this now only with blocked pawns.

EDIT:
I have later tried but only with the full penalty.

[31m059]

@Rocky640 Also, as @Vizvezdenec mentioned on the test itself, it makes sense to consider this patch as a form of compensation for a recent commit db59696, which increases the space weight with the number of blocked pawns. To my understanding, that should favor White in most French Advance (3. e5) structures. This helps offset that a bit.

[vondele]

Thanks!

[xoto10]

Regarding the advance French structure, @Lolligerhans made a good comment recently. Although the blocked pawns on d4/5 and e5/6 define the basic structure, perhaps we can gain by making sf play better when given this structure, instead of just trying to avoid it? e.g. I'm not good at chess, but even I can see that having blocked pawns on h5/6 as well as the ones mentioned above looks really bad, see game 28 in the current TCEC superfinal.

I'm not sure what that would mean we should look for, but I've already seen people looking at things like pieces trapped on 1st rank defending another pawn/piece, I've tried looking for >1 attacking pawn, and so on. Perhaps we need some combination of 2 or 3 factors, pawns unable to move, low space / mobility / trapped piece(s) / xxx ?