Author: Heiner Marxen
Date: 10:35:52 02/16/04
Go up one level in this thread
On February 16, 2004 at 10:31:03, Steven Edwards wrote: >Symbolic: The TNS (Thousand Node Search) > >The idea of limiting the cognitive search in Symbolic to under a thousand nodes >is based upon psychological studies that suggest top level human chessplayers >usually visualize between 100 and 1,000 positions per move in complex >middlegames. My personal time control upper limit preference for non-blitz >chess is a minute per move, and so the resulting target figure for node >frequency is about 20 Hz. > >One idea here is that the target frequency remain somewhat invariant of the host >hardware. On faster machines, the effort expended on non-search chess knowledge >can be increased, while on slower hardware, it can be lessened. Similar >throttling can be applied for different time controls on the same hardware. > >A distinction here between the large pool of iterative A/B searchers (and their >hardware brethren) vs programs like Paradise and Symbolic is the purpose of the >search itself. For the descendants of Slate and Atkin program Chess 4.x, the >main purpose is discovery. For Paradise, and for Symbolic to a slightly lesser >extent, the main purpose of the search is plan verification. Just from my personal introspection (when playing OTB, or analysing myself): I perform some (limited) searches without any valid plan, just to come up with some idea, what a plan could look like. Sometimes it is a goal I detect (like a defender needed for more than one piece), or a tactic aspect (like a pin that may be established (for whatever purpose)). (may be you knew all of this already ;-) >It is important to note that Symbolic is not a "selective search" program is the >commonly used sense of the phrase. A selective search program is one that >employs the Shannon type B strategy of reducing the full width search at each >node by applying a plausibility filter or by having a plausible move generator. >Shannon type B is the same as type A in that the purpose of the search is >discovery; the topography of the resulting depth first search trees may differ >in mean height and width, but the reasons for searching any particular node are >the same. What I mentioned above _is_ a search for disovery, but _not_ for discovery of a (forcably) achievable position, but rather for disovery of "plan fragments" or some such. Or is the plan "to find a plan" ? ;-) >Symbolic, like Paradise, should only expand a search node (i. e, move generation >plus selection) if it has a good reason to do so. The phrase "good reason" is >somewhat vague (at this point in development), but the one thing it does not >mean is "there's still time on the clock, so let's try another move/another >iteration". Instead, Symbolic will always have an active plan that will >determine which nodes to expand. In some cases, multiple moves at a given node >will be conforming to the current plan. In others, perhaps no move will >suffice, so the plan must be modified or abandoned. As Symbolic keeps the >entire search tree available at all times, a node may be revisited with >different plans. > >And although the exact implementation details of the above phrase "good reason" >are not well defined at this point, it is guaranteed that each "good reason" >will have a natural language representation. Thus, another reason for the TNS That is a very good idea IMHO. Especially as it forces _you_ to make explicit (part of) your method. OTOH, I would not object to usage of a few newly invented terms/words, here. Such terms could be globally defined (by you, the programmer), or locally, by Symbolic, for just one generated "explanation". >node count limitation: Symbolic will produce an explanation audit trail with all >of the good reasons, in English, for each decision made during the search and >this document has to be easily readable (by me) for the purposes of tutoring the >program. A multi-megabyte dump will not be useful, but a five or six page >synopsis should work well. I admire your (obviously serious) effort to do AI in chess. Da capo! Cheers, Heiner
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.