How to get the "usual" Multi PV with MCTS engines?

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Laskos
Posts: 9417
Joined: Wed Jul 26, 2006 8:21 pm
Full name: Kai Laskos

How to get the "usual" Multi PV with MCTS engines?

Post by Laskos » Tue May 21, 2019 8:39 am

I want already to rewrite the basis of the opening theory using Lc0, being an 1700 Elo player :lol:.

Now, a bit more seriously, I am confident that late nets of the T30 and T40 runs are VERY strong in the openings (provably MUCH stronger than any standard AB engine). So, I let Lc0 21.2rc1 with a good late net ID42361 to analyze the starting opening position for as long as my RAM allows (in fact in the first run my machine crashed). My OC-ed RTX 2070 quickly (~15 min) fills all available RAM on my 16GB RAM machine. I set MultiPV = 20 for Lc0. Then I compared the output (after some 30 million nodes searched) to the human FIDE Elo above 2200 statistic from the "Chess Tempo" site. The comparison is here:

=
Initial_position_H_Lc0.jpg
Initial_position_H_Lc0.jpg (211.57 KiB) Viewed 1399 times
=


Many curious and interesting things can be said from these numbers, but for now I want to focus on say last 12 of possible opening moves. The statistic of strong human players becomes weak...but so is the MCTS tree search there even in MultiPV mode with both Lc0 and Komodo MCTS. The search tree is shallow and narrow on these moves and they have few visits. With AB engines and usual MultiPV, I don't have such worries about the weaker moves. More or less, all are explored to a similar degree. So, with MCTS, if I really want to see how say a4 move in the opening shows itself, I do have to play it, right? Is there a way to have a "regular" MultiPV (similar to that of AB engines) with MCTS engines?

chrisw
Posts: 2020
Joined: Tue Apr 03, 2012 2:28 pm

Re: How to get the "usual" Multi PV with MCTS engines?

Post by chrisw » Tue May 21, 2019 9:13 am

Laskos wrote:
Tue May 21, 2019 8:39 am
I want already to rewrite the basis of the opening theory using Lc0, being an 1700 Elo player :lol:.

Now, a bit more seriously, I am confident that late nets of the T30 and T40 runs are VERY strong in the openings (provably MUCH stronger than any standard AB engine). So, I let Lc0 21.2rc1 with a good late net ID42361 to analyze the starting opening position for as long as my RAM allows (in fact in the first run my machine crashed). My OC-ed RTX 2070 quickly (~15 min) fills all available RAM on my 16GB RAM machine. I set MultiPV = 20 for Lc0. Then I compared the output (after some 30 million nodes searched) to the human FIDE Elo above 2200 statistic from the "Chess Tempo" site. The comparison is here:

=
Initial_position_H_Lc0.jpg

=


Many curious and interesting things can be said from these numbers, but for now I want to focus on say last 12 of possible opening moves. The statistic of strong human players becomes weak...but so is the MCTS tree search there even in MultiPV mode with both Lc0 and Komodo MCTS. The search tree is shallow and narrow on these moves and they have few visits. With AB engines and usual MultiPV, I don't have such worries about the weaker moves. More or less, all are explored to a similar degree. So, with MCTS, if I really want to see how say a4 move in the opening shows itself, I do have to play it, right? Is there a way to have a "regular" MultiPV (similar to that of AB engines) with MCTS engines?
Assuming you don’t want to actually attack the source code and recompile ...
Modify the PUCT to give more width, less depth, but that will basically destroy the effectiveness of the search.
Play each move and then search (you already suggested that).
Write a little program in Python to launch several instances of LC0, spreading the available RAM and GPU between them, running in parallel, each one handling one root move.
Write a little Python program that serially runs each root move.

Probably what you would really want, is a recompiled LC0 source that allowed you to remove moves from the root move list. Then the search could concentrate on what remained. That would be relatively easy for Crem or someone to do, you would just pass in a command with a list of skip moves (or a list of do moves).

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Guenther
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Re: How to get the "usual" Multi PV with MCTS engines?

Post by Guenther » Tue May 21, 2019 9:33 am

chrisw wrote:
Tue May 21, 2019 9:13 am
Laskos wrote:
Tue May 21, 2019 8:39 am
I want already to rewrite the basis of the opening theory using Lc0, being an 1700 Elo player :lol:.

Now, a bit more seriously, I am confident that late nets of the T30 and T40 runs are VERY strong in the openings (provably MUCH stronger than any standard AB engine). So, I let Lc0 21.2rc1 with a good late net ID42361 to analyze the starting opening position for as long as my RAM allows (in fact in the first run my machine crashed). My OC-ed RTX 2070 quickly (~15 min) fills all available RAM on my 16GB RAM machine. I set MultiPV = 20 for Lc0. Then I compared the output (after some 30 million nodes searched) to the human FIDE Elo above 2200 statistic from the "Chess Tempo" site. The comparison is here:

=
Initial_position_H_Lc0.jpg

=


Many curious and interesting things can be said from these numbers, but for now I want to focus on say last 12 of possible opening moves. The statistic of strong human players becomes weak...but so is the MCTS tree search there even in MultiPV mode with both Lc0 and Komodo MCTS. The search tree is shallow and narrow on these moves and they have few visits. With AB engines and usual MultiPV, I don't have such worries about the weaker moves. More or less, all are explored to a similar degree. So, with MCTS, if I really want to see how say a4 move in the opening shows itself, I do have to play it, right? Is there a way to have a "regular" MultiPV (similar to that of AB engines) with MCTS engines?
Assuming you don’t want to actually attack the source code and recompile ...
Modify the PUCT to give more width, less depth, but that will basically destroy the effectiveness of the search.
Play each move and then search (you already suggested that).
Write a little program in Python to launch several instances of LC0, spreading the available RAM and GPU between them, running in parallel, each one handling one root move.
Write a little Python program that serially runs each root move.

Probably what you would really want, is a recompiled LC0 source that allowed you to remove moves from the root move list. Then the search could concentrate on what remained. That would be relatively easy for Crem or someone to do, you would just pass in a command with a list of skip moves (or a list of do moves).
The uci option 'searchmoves' should do this. I assume LC0 does not support this currently? (never tried it).

Code: Select all

* go
	start calculating on the current position set up with the "position" command.
	There are a number of commands that can follow this command, all will be sent in the same string.
	If one command is not send its value should be interpreted as it would not influence the search.
	* searchmoves  .... 
		restrict search to this moves only
		Example: After "position startpos" and "go infinite searchmoves e2e4 d2d4"
		the engine should only search the two moves e2e4 and d2d4 in the initial position.
Current foe list count : [93]
http://rwbc-chess.de/chronology.htm

User avatar
Laskos
Posts: 9417
Joined: Wed Jul 26, 2006 8:21 pm
Full name: Kai Laskos

Re: How to get the "usual" Multi PV with MCTS engines?

Post by Laskos » Tue May 21, 2019 10:13 am

chrisw wrote:
Tue May 21, 2019 9:13 am
Laskos wrote:
Tue May 21, 2019 8:39 am
I want already to rewrite the basis of the opening theory using Lc0, being an 1700 Elo player :lol:.

Now, a bit more seriously, I am confident that late nets of the T30 and T40 runs are VERY strong in the openings (provably MUCH stronger than any standard AB engine). So, I let Lc0 21.2rc1 with a good late net ID42361 to analyze the starting opening position for as long as my RAM allows (in fact in the first run my machine crashed). My OC-ed RTX 2070 quickly (~15 min) fills all available RAM on my 16GB RAM machine. I set MultiPV = 20 for Lc0. Then I compared the output (after some 30 million nodes searched) to the human FIDE Elo above 2200 statistic from the "Chess Tempo" site. The comparison is here:

=
Initial_position_H_Lc0.jpg

=


Many curious and interesting things can be said from these numbers, but for now I want to focus on say last 12 of possible opening moves. The statistic of strong human players becomes weak...but so is the MCTS tree search there even in MultiPV mode with both Lc0 and Komodo MCTS. The search tree is shallow and narrow on these moves and they have few visits. With AB engines and usual MultiPV, I don't have such worries about the weaker moves. More or less, all are explored to a similar degree. So, with MCTS, if I really want to see how say a4 move in the opening shows itself, I do have to play it, right? Is there a way to have a "regular" MultiPV (similar to that of AB engines) with MCTS engines?
Assuming you don’t want to actually attack the source code and recompile ...
Modify the PUCT to give more width, less depth, but that will basically destroy the effectiveness of the search.
Play each move and then search (you already suggested that).
Write a little program in Python to launch several instances of LC0, spreading the available RAM and GPU between them, running in parallel, each one handling one root move.
Write a little Python program that serially runs each root move.

Probably what you would really want, is a recompiled LC0 source that allowed you to remove moves from the root move list. Then the search could concentrate on what remained. That would be relatively easy for Crem or someone to do, you would just pass in a command with a list of skip moves (or a list of do moves).
Thanks, I think I have to content myself with serially running the positions, maybe using Python. I had bad experiences with spreading GPU on several parallel instances of Lc0, they are GPU hungry and seem unstable or slowing down too much when in parallel. Guenther's UCI option would be useful if it will be available.
What PUCT and/or other parameters would give equal distribution of visited moves (equal distribution policy head, right?)? I am not interested in the quality of the chosen best move, but in the quality of several or all possible moves.

chrisw
Posts: 2020
Joined: Tue Apr 03, 2012 2:28 pm

Re: How to get the "usual" Multi PV with MCTS engines?

Post by chrisw » Tue May 21, 2019 11:37 am

Laskos wrote:
Tue May 21, 2019 10:13 am
chrisw wrote:
Tue May 21, 2019 9:13 am
Laskos wrote:
Tue May 21, 2019 8:39 am
I want already to rewrite the basis of the opening theory using Lc0, being an 1700 Elo player :lol:.

Now, a bit more seriously, I am confident that late nets of the T30 and T40 runs are VERY strong in the openings (provably MUCH stronger than any standard AB engine). So, I let Lc0 21.2rc1 with a good late net ID42361 to analyze the starting opening position for as long as my RAM allows (in fact in the first run my machine crashed). My OC-ed RTX 2070 quickly (~15 min) fills all available RAM on my 16GB RAM machine. I set MultiPV = 20 for Lc0. Then I compared the output (after some 30 million nodes searched) to the human FIDE Elo above 2200 statistic from the "Chess Tempo" site. The comparison is here:

=
Initial_position_H_Lc0.jpg

=


Many curious and interesting things can be said from these numbers, but for now I want to focus on say last 12 of possible opening moves. The statistic of strong human players becomes weak...but so is the MCTS tree search there even in MultiPV mode with both Lc0 and Komodo MCTS. The search tree is shallow and narrow on these moves and they have few visits. With AB engines and usual MultiPV, I don't have such worries about the weaker moves. More or less, all are explored to a similar degree. So, with MCTS, if I really want to see how say a4 move in the opening shows itself, I do have to play it, right? Is there a way to have a "regular" MultiPV (similar to that of AB engines) with MCTS engines?
Assuming you don’t want to actually attack the source code and recompile ...
Modify the PUCT to give more width, less depth, but that will basically destroy the effectiveness of the search.
Play each move and then search (you already suggested that).
Write a little program in Python to launch several instances of LC0, spreading the available RAM and GPU between them, running in parallel, each one handling one root move.
Write a little Python program that serially runs each root move.

Probably what you would really want, is a recompiled LC0 source that allowed you to remove moves from the root move list. Then the search could concentrate on what remained. That would be relatively easy for Crem or someone to do, you would just pass in a command with a list of skip moves (or a list of do moves).
Thanks, I think I have to content myself with serially running the positions, maybe using Python. I had bad experiences with spreading GPU on several parallel instances of Lc0, they are GPU hungry and seem unstable or slowing down too much when in parallel. Guenther's UCI option would be useful if it will be available.
What PUCT and/or other parameters would give equal distribution of visited moves (equal distribution policy head, right?)? I am not interested in the quality of the chosen best move, but in the quality of several or all possible moves.
actually, now I think about it, it's quite easy, and could be done without destroying the PUCT. Ask Crem to have a source code modification and command line option to choose to search each root move equally (ie no PUCT at root). Unfortunately, LC0 won't then be able to choose a root move based on visit count (they'll all be the same), but could choose instead on winrate. Basically, you wouldn't want the PUCT different when in tree, but only at the root.
It will degrade LC0 gameplay, but probably no more than multiPV degrades AB gameplay.

Ferdy
Posts: 4085
Joined: Sun Aug 10, 2008 1:15 pm
Location: Philippines

Re: How to get the "usual" Multi PV with MCTS engines?

Post by Ferdy » Tue May 21, 2019 1:48 pm

Guenther wrote:
Tue May 21, 2019 9:33 am
chrisw wrote:
Tue May 21, 2019 9:13 am
Laskos wrote:
Tue May 21, 2019 8:39 am
I want already to rewrite the basis of the opening theory using Lc0, being an 1700 Elo player :lol:.

Now, a bit more seriously, I am confident that late nets of the T30 and T40 runs are VERY strong in the openings (provably MUCH stronger than any standard AB engine). So, I let Lc0 21.2rc1 with a good late net ID42361 to analyze the starting opening position for as long as my RAM allows (in fact in the first run my machine crashed). My OC-ed RTX 2070 quickly (~15 min) fills all available RAM on my 16GB RAM machine. I set MultiPV = 20 for Lc0. Then I compared the output (after some 30 million nodes searched) to the human FIDE Elo above 2200 statistic from the "Chess Tempo" site. The comparison is here:

=
Initial_position_H_Lc0.jpg

=


Many curious and interesting things can be said from these numbers, but for now I want to focus on say last 12 of possible opening moves. The statistic of strong human players becomes weak...but so is the MCTS tree search there even in MultiPV mode with both Lc0 and Komodo MCTS. The search tree is shallow and narrow on these moves and they have few visits. With AB engines and usual MultiPV, I don't have such worries about the weaker moves. More or less, all are explored to a similar degree. So, with MCTS, if I really want to see how say a4 move in the opening shows itself, I do have to play it, right? Is there a way to have a "regular" MultiPV (similar to that of AB engines) with MCTS engines?
Assuming you don’t want to actually attack the source code and recompile ...
Modify the PUCT to give more width, less depth, but that will basically destroy the effectiveness of the search.
Play each move and then search (you already suggested that).
Write a little program in Python to launch several instances of LC0, spreading the available RAM and GPU between them, running in parallel, each one handling one root move.
Write a little Python program that serially runs each root move.

Probably what you would really want, is a recompiled LC0 source that allowed you to remove moves from the root move list. Then the search could concentrate on what remained. That would be relatively easy for Crem or someone to do, you would just pass in a command with a list of skip moves (or a list of do moves).
The uci option 'searchmoves' should do this. I assume LC0 does not support this currently? (never tried it).

Code: Select all

* go
	start calculating on the current position set up with the "position" command.
	There are a number of commands that can follow this command, all will be sent in the same string.
	If one command is not send its value should be interpreted as it would not influence the search.
	* searchmoves  .... 
		restrict search to this moves only
		Example: After "position startpos" and "go infinite searchmoves e2e4 d2d4"
		the engine should only search the two moves e2e4 and d2d4 in the initial position.
searchmoves is supported by Lc0. Tried this before in aquiarium IDEA.

Ferdy
Posts: 4085
Joined: Sun Aug 10, 2008 1:15 pm
Location: Philippines

Re: How to get the "usual" Multi PV with MCTS engines?

Post by Ferdy » Tue May 21, 2019 2:02 pm

Laskos wrote:
Tue May 21, 2019 10:13 am
chrisw wrote:
Tue May 21, 2019 9:13 am
Laskos wrote:
Tue May 21, 2019 8:39 am
I want already to rewrite the basis of the opening theory using Lc0, being an 1700 Elo player :lol:.

Now, a bit more seriously, I am confident that late nets of the T30 and T40 runs are VERY strong in the openings (provably MUCH stronger than any standard AB engine). So, I let Lc0 21.2rc1 with a good late net ID42361 to analyze the starting opening position for as long as my RAM allows (in fact in the first run my machine crashed). My OC-ed RTX 2070 quickly (~15 min) fills all available RAM on my 16GB RAM machine. I set MultiPV = 20 for Lc0. Then I compared the output (after some 30 million nodes searched) to the human FIDE Elo above 2200 statistic from the "Chess Tempo" site. The comparison is here:

=
Initial_position_H_Lc0.jpg

=


Many curious and interesting things can be said from these numbers, but for now I want to focus on say last 12 of possible opening moves. The statistic of strong human players becomes weak...but so is the MCTS tree search there even in MultiPV mode with both Lc0 and Komodo MCTS. The search tree is shallow and narrow on these moves and they have few visits. With AB engines and usual MultiPV, I don't have such worries about the weaker moves. More or less, all are explored to a similar degree. So, with MCTS, if I really want to see how say a4 move in the opening shows itself, I do have to play it, right? Is there a way to have a "regular" MultiPV (similar to that of AB engines) with MCTS engines?
Assuming you don’t want to actually attack the source code and recompile ...
Modify the PUCT to give more width, less depth, but that will basically destroy the effectiveness of the search.
Play each move and then search (you already suggested that).
Write a little program in Python to launch several instances of LC0, spreading the available RAM and GPU between them, running in parallel, each one handling one root move.
Write a little Python program that serially runs each root move.

Probably what you would really want, is a recompiled LC0 source that allowed you to remove moves from the root move list. Then the search could concentrate on what remained. That would be relatively easy for Crem or someone to do, you would just pass in a command with a list of skip moves (or a list of do moves).
Thanks, I think I have to content myself with serially running the positions, maybe using Python. I had bad experiences with spreading GPU on several parallel instances of Lc0, they are GPU hungry and seem unstable or slowing down too much when in parallel. Guenther's UCI option would be useful if it will be available.
What PUCT and/or other parameters would give equal distribution of visited moves (equal distribution policy head, right?)? I am not interested in the quality of the chosen best move, but in the quality of several or all possible moves.
Without revising the code, I think your idea of moving the candidate move on the board and then search to a fix time or nodes or depth, get the score, invert the score sign, is a good idea.

mjlef
Posts: 1424
Joined: Thu Mar 30, 2006 12:08 pm
Contact:

Re: How to get the "usual" Multi PV with MCTS engines?

Post by mjlef » Tue May 21, 2019 2:25 pm

Laskos wrote:
Tue May 21, 2019 8:39 am
I want already to rewrite the basis of the opening theory using Lc0, being an 1700 Elo player :lol:.

Now, a bit more seriously, I am confident that late nets of the T30 and T40 runs are VERY strong in the openings (provably MUCH stronger than any standard AB engine). So, I let Lc0 21.2rc1 with a good late net ID42361 to analyze the starting opening position for as long as my RAM allows (in fact in the first run my machine crashed). My OC-ed RTX 2070 quickly (~15 min) fills all available RAM on my 16GB RAM machine. I set MultiPV = 20 for Lc0. Then I compared the output (after some 30 million nodes searched) to the human FIDE Elo above 2200 statistic from the "Chess Tempo" site. The comparison is here:

=
Initial_position_H_Lc0.jpg

=


Many curious and interesting things can be said from these numbers, but for now I want to focus on say last 12 of possible opening moves. The statistic of strong human players becomes weak...but so is the MCTS tree search there even in MultiPV mode with both Lc0 and Komodo MCTS. The search tree is shallow and narrow on these moves and they have few visits. With AB engines and usual MultiPV, I don't have such worries about the weaker moves. More or less, all are explored to a similar degree. So, with MCTS, if I really want to see how say a4 move in the opening shows itself, I do have to play it, right? Is there a way to have a "regular" MultiPV (similar to that of AB engines) with MCTS engines?
neat stuff. I could add a mode to Komodo so that when in MultiPV mode, it would simply visit all root nodes evenly. This would force it to Explore them all equally. But this will greatly reduce the overall depth of the best lines (and lengthen those of the not good lines). I would not expect it to do very well, but could be an interesting experiment.

chrisw
Posts: 2020
Joined: Tue Apr 03, 2012 2:28 pm

Re: How to get the "usual" Multi PV with MCTS engines?

Post by chrisw » Tue May 21, 2019 2:26 pm

Ferdy wrote:
Tue May 21, 2019 2:02 pm
Laskos wrote:
Tue May 21, 2019 10:13 am
chrisw wrote:
Tue May 21, 2019 9:13 am
Laskos wrote:
Tue May 21, 2019 8:39 am
I want already to rewrite the basis of the opening theory using Lc0, being an 1700 Elo player :lol:.

Now, a bit more seriously, I am confident that late nets of the T30 and T40 runs are VERY strong in the openings (provably MUCH stronger than any standard AB engine). So, I let Lc0 21.2rc1 with a good late net ID42361 to analyze the starting opening position for as long as my RAM allows (in fact in the first run my machine crashed). My OC-ed RTX 2070 quickly (~15 min) fills all available RAM on my 16GB RAM machine. I set MultiPV = 20 for Lc0. Then I compared the output (after some 30 million nodes searched) to the human FIDE Elo above 2200 statistic from the "Chess Tempo" site. The comparison is here:

=
Initial_position_H_Lc0.jpg

=


Many curious and interesting things can be said from these numbers, but for now I want to focus on say last 12 of possible opening moves. The statistic of strong human players becomes weak...but so is the MCTS tree search there even in MultiPV mode with both Lc0 and Komodo MCTS. The search tree is shallow and narrow on these moves and they have few visits. With AB engines and usual MultiPV, I don't have such worries about the weaker moves. More or less, all are explored to a similar degree. So, with MCTS, if I really want to see how say a4 move in the opening shows itself, I do have to play it, right? Is there a way to have a "regular" MultiPV (similar to that of AB engines) with MCTS engines?
Assuming you don’t want to actually attack the source code and recompile ...
Modify the PUCT to give more width, less depth, but that will basically destroy the effectiveness of the search.
Play each move and then search (you already suggested that).
Write a little program in Python to launch several instances of LC0, spreading the available RAM and GPU between them, running in parallel, each one handling one root move.
Write a little Python program that serially runs each root move.

Probably what you would really want, is a recompiled LC0 source that allowed you to remove moves from the root move list. Then the search could concentrate on what remained. That would be relatively easy for Crem or someone to do, you would just pass in a command with a list of skip moves (or a list of do moves).
Thanks, I think I have to content myself with serially running the positions, maybe using Python. I had bad experiences with spreading GPU on several parallel instances of Lc0, they are GPU hungry and seem unstable or slowing down too much when in parallel. Guenther's UCI option would be useful if it will be available.
What PUCT and/or other parameters would give equal distribution of visited moves (equal distribution policy head, right?)? I am not interested in the quality of the chosen best move, but in the quality of several or all possible moves.
Without revising the code, I think your idea of moving the candidate move on the board and then search to a fix time or nodes or depth, get the score, invert the score sign, is a good idea.
That sounds about right.
An automated extension of that idea would be, via a little bit of Python:
Carry out a normal search for N nodes.
Get the searched moves and each visit count and each win rate.
Then, for each move, except the first (most visited), play it on board and search for X nodes, where X is the difference between visits[0] and visits. Get score, invert as above.
Then score(i) = mean score of the two scores weighted by their visits.

Does that sound right?

chrisw
Posts: 2020
Joined: Tue Apr 03, 2012 2:28 pm

Re: How to get the "usual" Multi PV with MCTS engines?

Post by chrisw » Tue May 21, 2019 2:29 pm

mjlef wrote:
Tue May 21, 2019 2:25 pm
Laskos wrote:
Tue May 21, 2019 8:39 am
I want already to rewrite the basis of the opening theory using Lc0, being an 1700 Elo player :lol:.

Now, a bit more seriously, I am confident that late nets of the T30 and T40 runs are VERY strong in the openings (provably MUCH stronger than any standard AB engine). So, I let Lc0 21.2rc1 with a good late net ID42361 to analyze the starting opening position for as long as my RAM allows (in fact in the first run my machine crashed). My OC-ed RTX 2070 quickly (~15 min) fills all available RAM on my 16GB RAM machine. I set MultiPV = 20 for Lc0. Then I compared the output (after some 30 million nodes searched) to the human FIDE Elo above 2200 statistic from the "Chess Tempo" site. The comparison is here:

=
Initial_position_H_Lc0.jpg

=


Many curious and interesting things can be said from these numbers, but for now I want to focus on say last 12 of possible opening moves. The statistic of strong human players becomes weak...but so is the MCTS tree search there even in MultiPV mode with both Lc0 and Komodo MCTS. The search tree is shallow and narrow on these moves and they have few visits. With AB engines and usual MultiPV, I don't have such worries about the weaker moves. More or less, all are explored to a similar degree. So, with MCTS, if I really want to see how say a4 move in the opening shows itself, I do have to play it, right? Is there a way to have a "regular" MultiPV (similar to that of AB engines) with MCTS engines?
neat stuff. I could add a mode to Komodo so that when in MultiPV mode, it would simply visit all root nodes evenly. This would force it to Explore them all equally. But this will greatly reduce the overall depth of the best lines (and lengthen those of the not good lines). I would not expect it to do very well, but could be an interesting experiment.
Don’t forget to credit my post above for the original idea, else somebody might do a Dark Triad Rybka on you.

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