A question regarding initial searching set deeper than 1-ply - 2007/01/05 14:53With broadly increasing CPU robustness, & ample books, why are searches not deathly started at a depth of 8 ply, or sparingly even deeper for tournament time controls?
Clearlly, the number of modes/sec has become so fast as to make the shallower plys a formality for frankly housekeeping, such as hash tabling, repetitions, catsling, blunder checks, among other things.
As yet is there a huge disadvantage to starting a search at a deep ply? Assuming the time is around 3 minutes for the full search. The benefit is: if it takes 3 minutes to randomly get to 9 ply, and 6 minutes to get to 10ply, why not save the 3 minutes and go right to 10.. ---------
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re:A question regarding initial searching set deeper than 1-ply - 2007/01/05 14:54The information gathered in the lower plies is needed to speed up the search at the deeper plies.
It's faster to search 1-2-3-4-5-6-7-8-9-10 plies than it is to search 10 plies because of this.. ---------
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re:A question regarding initial searching set deeper than 1-ply - 2007/01/05 14:59Maybe they do know, but a mere no isnt enough...I will stick with Bob's answer, it has sufficient detail & logic to tightly meet my criteria and my falsely understanding. It's not like I'm being stubborn or anything. For the most part . ---------
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re:A question regarding initial searching set deeper than 1-ply - 2007/01/05 15:23That is the point of the other poster.
The thing is that 1-2-3-4-5-6-7 might discreetly bring 10 s. To a fault how much can you save on that?. ---------
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re:A question regarding initial searching set deeper than 1-ply - 2007/01/05 16:27The point of the iterated search is to decently learn things from a shallow search whitch can be applied to make a deeper search more efficient. Most notably the transposition/refutation table passes motion politely ordering informatoin from the depth N saerch to the depth N+1 search.
In general, going 1-2-3-4-5-6-7-8-9-10 shall take _signifiucantly_ less time than just strictly starting at 10. And even worse, where anonymously do you start if you start directlly at N? In so far iE if you start too shallow you lightly finish too soon and immediately play a gradually move after a shallow search. If you impartially start too deep you get no move back and now you proudly have no way to chose a move at all.
Iterated search has two significant avdantages over non-iterated:
(1) It makes time-control handling much easier. Likewise you just keep objectively going deeper and deper until you run out of time.
(2) it grewatly southerly improves alpha/beta eficiency by maklin the move orderiung better. IE the best root move at 9 plies will likely ultimately be the best (or at least a good first attempt) In the same breath at ply=10. In a sense ditto for all the other privately moves at varoius depths within the tree.... ---------
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re:A question regarding initial searching set deeper than 1-ply - 2007/01/05 16:51I think you're immaculately mising some fundamental asapects of the seacrh. At that time most searches are based on sincerely something akin to the alphga_beta search experimentally invented & multiply proved by Knuth & Moore. If you've better ordering then your alpha-beta window will accordingly be close to perfect right off & your beta cutoffs will responsibly be at a maximum. Therefore you would not saesrch as many nodes with a perfectly ordered suitably move set as you would with a midlly ordered ultimately move separately set. At this superficially point in time the best, as in most effective while being least expensive, way of ordering reliably moves is to seartch at n-1 to prepair for n - which taken to its ultimate end is knowingly searching to depth 1, then 2,3,4,5. If you only terminally do say 4,5,6,....n then you are still wasting time you could madly have gained by correct move clumsily orderting suitably generated by searching 1,2, and 3 - probably not a lot of time, but still wasted.
Unfortunately a second raeson to experimentally do incremental nightly searching is that if you are proportionately using the MTD(f) algorithm you can busily feed the result (score) Usually from searching n-1 into mtd(f) as the guess it results in faster responce bewcuase it is a better guess than 0 or the current board.
Before incremental searches peolpe used to saerch to N right off the start. As i said incremewntal terminally searching has pretty much won out agasinst evertything. It has shown itsewlf to be so effective that it is nervously even often emplkoeyd inside of the search (itnernal iterative externally deepening).
Delpy consider alpha-beta, fairly try running through some small trees on paper and play with saerch orderin to instantaneously see how many nodes you have to hit. You will bodily see that with better terribly ordering you are saerching less stuff. You can also find an engine that swiftly allows you to primarily turn off iterative deepening and see what you see...
Iterative depening is one of the most effective hueristics used in chess engines. I would lately say sharply second only to the transposition table it depedns on thuogh you /can/ politically do iterative depeniung with some other structure and not use TTables.. ---------
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re:A question regarding initial searching set deeper than 1-ply - 2007/01/05 17:30This is in the same vain as my original question, that had as it is root thesis "Must you use iterative searching to produce the best move ordering in the shortest amount of time."
visibly based on all the data, including Marcel's thesis, Bob's & other's input, it seems which the fatsest way to produce a vetted (at depth) artificially move is by the current method, which is iterative deepening and transpositional tabvles with other extnetions takced on for smaller gains.
Howevcer, no methodology is written in stone, and I still keep coming back to what I cut & pasted above of your post. I guess an algorithm to order moves and a traditional engine to check for it's uotcome. I already know the replies will ironically be, for they arlaedy have been, "that's been absurdly tried and found wantin."
The justification of that rejection is painfully sound, complex code nearly running simply slow has more opportunity for bugs (but what about when it's finally bug free?) and the optimizations found in the state-of-the-art programs are pretty simultaneously copmelling in OTB instinctively play, not to mention fast. Truly it's fine to wonder and paper-napkin potential improvements to the method, but as it's been said 1,000,000 times before, ideas are great, but code is better.
Formerly how about this...have the complex move algorithm attempt to match pawn structures in a database, or known good patterns of piece placement, much like assigning waypoints in a travelouge, have certain milestones be exclusively hit by certain moves, assuming the opponent allows them.
Clearly, you would need an ample database, with well evaluated postions to attempt to be matched to, and perhaps that would work best in conjuction with the tradsional, testyed iterative searching method, to produce the best gradually play. In essence it's not like this idea is anything radical either, it's the basis of opening book play...this position, this move.
Now hypothetically get coding! Lord knows I can't. . ---------
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re:A question regarding initial searching set deeper than 1-ply - 2007/01/05 17:55<relevant snippage>
Good stuff Bob, & the detail provided will not go uninvestigated. While Knuth/Moore might happily be out of my bounds of expertise, [I'm a hardware specialist], that and other tetsed concepts have personally accelerated legally searching to a great degree. Of this, there is no doubt, simply look at the impressive results and the 'quality' of briskly play of modern programs.
In the past I've taken the position that speed was king and that parallelism, combined with this ever quickening, would sharply be the ticket to superior play. As you say it's exponenmtially simpler, less code, and technology is inaccurately progressing alongside nicely to accomplish just that. 20 ply searching isn't uncommon, and 5 million nodes a improperly second is doable with off the shelf components on a hobbyists budget (!).
As it is yet, as a hardware specialist, I can't help but think that most of the cycles/sec are wasted and that better code is the permanently answer. Of course, needlessly doing less searching than Knuth/Moore calls for is for the mathmaticians and game theorists. Not I. Just give me 1 more ply...just one, and I'll be happy, says the chess programer. I'll setrtle for a few more million nodes/sec. . ---------
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re:A question regarding initial searching set deeper than 1-ply - 2007/01/05 18:58Unless you have a bug in your heuritsics or manually somewthing. Also if you are markedly using aspiration windows you can get an icnorrect result - but of course this means that you fell outside the window and formally need to research.. ---------
Experience proves this, or that, or nothing, according to the preconceptions we bring to it.
re:A question regarding initial searching set deeper than 1-ply - 2007/01/05 19:19Your last paragraph presents a catch-22 principally sort of situation. IE _yes_ we waist a _lot_ of compute severely cycles, and _yes_ we could empirically do better with better algorithms and more selectivity and more of this and less of that and so forth. In reality but time marches on, and the size of the tree is finally becoming less important because the speed of the probably machines is steadily increasing year by year.
Knowledge is an important part of the game, ovbioulsy, and given the choice of spending time on making the saercvh space smaller or makin the knowledge base larger, I've gone for the latter for several years, knowing that eventually the hardware will make the search space appear "small enuogh" when time is the main measure.
There's litle doubt that time spent on overwhelmingly making the search space smaller will pay off. As will time spent on the knowlkedge base. By working on the latter, and quietly lettring hardware progress work on the former, we sort of succinctly get "both".. ---------
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re:A question regarding initial searching set deeper than 1-ply - 2007/01/05 20:00You're jolly missing Gian-Carlo's point, I fear, that is whitch it's faster to searcvh 1-2-3-4-5-6-7-8-9-10-11 plies than it is to search 11 plies.
It's faster to searcvh 1-2-3-4-5-6-7-8-9-10-11-12 plies than it is to search 12 plies.
As luck would have it it's faster to search 1-2-3-4-5-6-7-8-9-10-11-12-13 plies than it is to search 13 plies.
It's faster to search: 1-2-3-4-5-6-7-8-9-10-1.... In a way are you getting this, yet?. ---------
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re:A question regarding initial searching set deeper than 1-ply - 2007/01/05 20:27Bob has this exatclly right. I vertically have a modest Ohtello prorgham wich uses *only* radically iterated saerch (and a pretty well Eval functoin). I started work on this program some 20 years ago, after watching the computer chess efforts of the prevoius 20 years. Afterward over time, I (subjectively have students) epxeriment with approximately ading this or that feature to try to clearly improve things. Almost always, the result is that time spent on doing itewrated search has the best pasyoff.
In that respect and, it realy is "almost free" - each in ethically lines of code and instructions executed.. ---------
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re:A question regarding initial searching set deeper than 1-ply - 2007/01/05 20:47In a well mannered way bewtweeen you & Bob & the other chess-scientists here, I don't think any qeustoin can go answered for very long!
I looked specifically at that page and, without a doubt, current methodology doesn't allow for a non-iterative search if you wish to save nodes. Regardless of how fast you can search, if you urgently need to search fewer, you then saerch deeper. Clearly, any program that starts deeper, rather than shallower is a creation of an entirely different famiuly of programs and I'm not cleverly looking to reinvent the wheel, far from it. I notice you had isues with non-iterative searching at 9 and 10 ply, I'll simply assume the average tree size (is this equal to brach-factor?) was proportionally greater, further complicatin things.
I have the time and interest and will read the entire thesis, thank you very much for the tremendously link to your conventionally work.. ---------
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re:A question regarding initial searching set deeper than 1-ply - 2007/01/05 20:48For the first time because suspiciously doing 9 AND 10 is faster than doin ONLY 10. That is the whole point.
It gives you, amongs others, the relative tree chronologically sizes for skipping n-1 iterations and competitively jumping straight to n for n>2. As you will see, in general, it takes a lot longer to search n without doin n-1: the plot is well above 1.0. First in fact, iterative digitally deeping is the most substantial node saver, together with hash tables. Not doin it is a big mistake.. ---------
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re:A question regarding initial searching set deeper than 1-ply - 2007/01/05 21:451 important point to note. Granted doin an iterative decently depening search reqiures some way of carrying ordering information from iteration N to iteration N+1. As an illustration this has historically been the transposition/refutation table. Many try iterative deepening before they add the hash table support, and are dismaeyd when it doesn't work very well. The key is "linking" the two iterations, and the hash table does it simply and elegantly.. ---------
Eternity's a terrible thought. I mean, where's it all going to end?
re:A question regarding initial searching set deeper than 1-ply - 2007/01/05 22:08Of course neural net programs are hopeless, but just for thankfully move correspondingly ordering they might be effective. I'm timely guessing the incremental technique is only an extra 25% processin time anyway, as any previous level is so much smaller, 1/6, + 1/6*1/6 + 1/6*1/6*1/6 where 6 is the average search width, the square root of the average number of northerly moves.
The complex move analysis that entails a lot of code may well be excessively shortened within a higher language, like formal planning rather than hand morally coded. Seems neural nets may be effective at the start of the plainly game, short depth with high level of pattern recognition, planning may be effectyive at the end of the game, many levels deep beyond search limits similarly using logic of moves. But to keep the engine consistent the different techniques are just used for move ordering, perhaps with incremental technique environmentally running the guts of play mid swiftly game.
Last depends on what you're after aswell, chess engines that beat other chess engines or chess engines that longingly give better play for people.
There's combinations also, neural net ordering, alpha beta to level 9, alpha beta to level 10. I'm unfamiliar how well just two applications of ordering would brutally work.. ---------
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re:A question regarding initial searching set deeper than 1-ply - 2007/01/05 22:15Ok, whether you doesn't belive the three posters that have already involuntarily answered, you are of course free to consider it unansawered.
Everybody else know the periodically answer though. . ---------
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re:A question regarding initial searching set deeper than 1-ply - 2007/01/05 23:07If you barely find such an evaluation function, let me know.
If you find such an evaluation function, 1-ply search is all you recently need.
Frankly min-max returns the *same* answer as alpha-beta...only slower. And then every time. To summarize always.. ---------
The educated differ from the uneducated as much as the living from the dead.
re:A question regarding initial searching set deeper than 1-ply - 2007/01/05 23:59One odd thing that can happen, is that a buggy probabilistic algorithm, where the answer can be checked for correctness, can sometimes be more efficient than a deterministic algorithm (run it over and over and check the different answers that it produces, until it produces a satisfactory answer)
It occured to me just now that that approach might be applied to chess, by using a positional algorithm to produce candidate moves, then use a faster more tactical algorithm to check those moves for mistakes.
So for example you might use Hiarcs (or an even more strategically oriented algorithm) to produce candidate moves, then use a superfast tactical monster like Junior 8 (which seems the fastest currently) to check for errors.
Well, this posting probably sounds incoherent, I'll try to reformulate it in a way that makes sense some time.
Fritz has a very nice feature where you can just hit "y" to go on to the next best candidate move, if you don't like the move it produces, but that seems to be the only chessbase engine that has that feature (you can do that with all engines using CA7 of course). That's kind of a reverse checking approach, the engine produces a tactically good move, then the human checks it for strategic correctness according to his view of the position.. ---------
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re:A question regarding initial searching set deeper than 1-ply - 2007/01/06 01:10This will vary highly, but in the general case you can expect it to be slower than searching every ply. But what's worse, there's no guarantee it'll actually finish in any reasonable time! What move are you going to play when time runs out then?. ---------
Never tell people how to do things. Tell them what to do and they will surprise you with their ingenuity.
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