This always attracted me as a concept and seems well received, per link above.
It should increase the branching factor considerably, and complicate its evaluation - not saying good or bad, just is.
Is branching factor actually that relevant? Just from writing some naive AIs for fun I got the impression that the only thing that actually mattered is how well you can evaluate a position without branching further. Whether you have 40 or 100 (or 1000) moves available, you usually just want to only look at "the best" 10-15 (ideally even less if you can), and how reliable this determining of "the best" is seems like a way larger factor than just how many branches there are in theory.
I dunno. Granted evaluation is key but so is branching, surely, as that is what generates new positions, and their complexity in evaluation as there are more factors to consider.
How does one 'look at "the best" 10-15 [positions]' without culling all the others first, however cheaply? I thought evaluation really was just tree searching (hence branching factor is crucial) with various weights (obviously this is traditional chess evaluation, not fancy NN stuff). I honestly am clueless.
This is, from my understanding, also the reason why traditional AI approaches struggled so much with Go. Not because Go has so many possible moves, but because given a certain game state it is so difficult to evaluate which player is ahead.
I think this is where the slight issue is. The branching factor of your game is related to but not the same as the branching factor of your search.
> I thought evaluation really was just tree searching (hence branching factor is crucial)
The most basic way would be to play every possible game through to completion, fully exploring the tree. If you have no way of estimating the value of a position you have to try it out and see what happens, and your branching factor of the game is the same as for your search. A small increase in possible moves makes an enormous difference - 5 to 10 for a 10 move game is a 1000x jump.
However, imagine the complete opposite. You have a perfect way of estimating your chance of winning for any particular board move. In that case, you'd just check all the moves you can make right now and not look any deeper in the tree. Going from 5 to 10 is a doubling of positions to check, no matter how many moves in the game.
Because of the exponential here, the number of positions to evaluate per move that you don't explore further is almost negligible (similarly it's easier to just calculate the size of the lowest expanded bit of the tree as that dominates the total).
So, the better you get at evaluating your position without searching, the more deeply you can explore because you're not branching off so much,
Gaining positional advantage at cost of anything other than pawn is probably not worth it. AFAIK in high level play gambits are not true gambits as you get the sacrifice back.
> Gaining positional advantage at cost of anything other than pawn is probably not worth it
This kind of post makes me want to give up on HN. I have actually played it (albeit a very long time ago) and you are wrong. Please try it.
But even if true, and only a pawn dies, it drastically changes the nature of the game as a white pawn is a barrier to white pieces. Make that barrier permeable and the entire game changes.
> Taking your own pieces would be sub-optimal choice in every-case other then avoiding mate
Or inflicting mate, if you're blocked from that by your own piece. Or opening an attack that otherwise blocked. Or freeing pieces otherwise useless (bishops seem to get this badly, though maybe it's just me - I was never a great player). Any major piece otherwise trapped can now escape by taking any lesser piece of its own that's fenced it in.
It totally changes the game. Position is just as important as pieces, and maybe more at different times.
And yet you have not brought up a single example.
It hard to imagine a self sacrifice that would be better than just taking a bad trade.