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Topic: Transposition table

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	Transposition Tables (Site not responding. Last check: 2007-10-10)
		Transposition tables (often referred to as hash tables) are used for storing chess positions during the search to avoid re-searching positions that can be reached via several different move sequences.
		Additionally, large transposition tables actually decrease the number of moves per second, because Sigma Chess then won't be able to use the processor cache properly.
		The remaining memory is assigned to the transposition tables.
	www.sigmachess.com /_usersmanual/ManualData/TransTables.html (618 words)

	Transposition table - Wikipedia, the free encyclopedia
		Such a table is a hash table of each of the positions analyzed so far up to a certain depth.
		It must be noted that the computation saved by a transposition table lookup is not just the evaluation of a single position - if that were the case, it would hardly be worth the effort, since evaluation functions are designed to be very fast anyway.
		Thus, transposition table entries for nodes at a lower depth in the game tree are more valuable (since the size of the subtree rooted at such a node is larger) and are therefore given more importance when the table fills up and some entries must be discarded.
	en.wikipedia.org /wiki/Transposition_table (739 words)

	From mads2@tott.kih.no Tue Oct 31 09:39:45 1995
		The computer can combine iterative deepening with various memory functions, particularly refutation and transposition tables, to reorder moves, so that at the next iteration its selected "principal variation" (best sequence of moves found during the previous iteration) is explored first.
		A transposition table serves as a cache memory and is used to store information about positions that have been visited before, usually during an earlier part of an iterative deepening search.
		Transposition tables are also invaluable as a means of extending search in the endgame, where only a few new moves emerge at each node, the others leading through transposition to positions that have been seen before.
	www.cs.ualberta.ca /~tony/ICCA/anatomy.html (2009 words)

	Tech info - Lokasoft (Site not responding. Last check: 2007-10-10)
		Transposition table is using by engine to store and retrieve data about previously searched positions.
		Bigger transposition table sizes will reduce at average the number of nodes to be searched to reach the same search result.
		That's why it is strongly recommended to use default value of pawn hash table size except cases in which you haven't enought RAM for it.
	www.lokasoft.nl /smarthink_tech_info (1109 words)

	Pawn Captures Wyvern: How Computer Chess Can Improve Your Pathfinding
		Transposition tables are normally constructed as closed hash tables, with hashing functions that are easy to update (such as a number of XOR operations) as one traverses the tree.
		In general, the move ordering benefits of combining iterative deepening and the transposition table are at least as important to the node count as the duplicate detection property, depending on the application chosen.
		In one experiment [Breuker 1996], half of the transposition table was reserved for the nodes closest to the root, and the other half of the transposition table was reserved for the most recently visited nodes regardless of depth.
	www.gamasutra.com /features/20000626/brockington_pfv.htm (5554 words)

	Hash table Summary
		Hash table array sizes are sometimes chosen to be prime numbers, or at least to be coprime with the numbers used to construct the hash value.
		With a power of two hash table size, often a permutation function is applied to the hash value before applying the bit masking operation.
		Hash tables require the design of an effective hash function for each key type, which in many situations is more difficult and time-consuming to design and debug than the mere comparison function required for a self-balancing binary search tree.
	www.bookrags.com /Hash_table (4785 words)

	hashing
		Assume that an entry in the transposition table (entry t) contains three pieces of data; the hash signature (the value used to confirm that this hash table entry represents the right position), the best move and the search result.
		When the program determines that it is time to store an entry into the transposition table, it computes the transposition table index by taking the low-order N bits of the hash signature, and using this as the table address where this 128-bit entry is to be stored.
		With today's large memories, it is not uncommon to have millions of transposition table entries.
	www.cis.uab.edu /info/faculty/hyatt/hashing.html (2168 words)

	[No title]
		CS 61B: Lecture 23 Friday, October 16 Transposition Tables: Using a Dictionary to Speed Game Trees ============================================================= An inefficiency of unadorned game tree search is that some grids can be reached through many different sequences of moves, and so the same grid might be evaluated many times at great expense.
		The table "defTable" must be long enough to accommodate pneumonoultramicroscopicsilicovolcanoconiosis, at 45 letters the longest word in the English language.
		Hash Tables (the most common implementation of dictionaries) ----------- Suppose n is the number of keys (words) whose definitions we want to store, and suppose we use a table of size s, where s is perhaps a little larger than n.
	www.cs.berkeley.edu /~jrs/61bf98/lectures/23/README (1274 words)

	Pente
		Transposition tables are used to store the values of a game state so they don't need to be recalculated should they occur again during a search.
		The hash table that I decided to use is a 3 dimensional array that stores "HashList" objects, which can hold as many table configurations as needed.
		The reason the hash table was made in 3 dimensions is that most of the possible base 3 strings will not occur, so most of the arrays will never be initialized, greatly reducing the amount of space the hash table occupies.
	www.cs.wisc.edu /~mjr/Pente/index.html (3881 words)

	The Main Transposition Table
		The main transposition table is an array of hash elements.
		Since many positions are apt to map to the same element in the hash table, the table elements contain a verification value, which can be used to make sure that the element in the table is the one that you are trying to find.
		Another problem that happens when you start using a transposition hash table, if you allow the search to cut off based upon elements in the table, is that your search suffers from instability.
	www.seanet.com /~brucemo/topics/hashing.htm (1232 words)

	Summary of Dennis Breuker's thesis
		For this purpose, a transposition table, holding the results of previous searches, is maintained in the remaining memory.
		In Chapter 2 three methods for improving the efficiency of a transposition table are described.
		However, beyond a certain table size not much is to be gained from doubling the number of positions.
	www.xs4all.nl /~breukerd/thesis/summary.html (930 words)

	GameDev.net -- Chess Programming Part II: Data Structures
		A transposition table is a repository of past search results, usually implemented as a hash dictionary or similar structure to achieve maximum speed.
		In situations where there are lots of possible transpositions (i.e., in the endgame, when there are few pieces on the board), the table quickly fills up with useful results and 90% or more of all positions generated will be found in it.
		Indexed only on the positions of pawns, this table requires little storage, and since there are comparatively few possible pawn moves, it changes so rarely that 99% of positions result in hash table hits.
	www.gamedev.net /reference/programming/features/chess2/page4.asp (634 words)

	Involvement of H-NS in Transpositional Recombination Mediated by IS1 -- Shiga et al. 183 (8): 2476 -- The Journal of ...
		The transposition activity of transposable elements is mediated by various host factors.
		Transposition of Mu DNA: joining of Mu to target DNA can be uncoupled from cleavage at the ends of Mu.
		Tn10 and IS10 transposition and chromosome rearrangements: mechanism and regulation in vivo and in vitro.
	jb.asm.org /cgi/content/full/183/8/2476 (5704 words)

	Repetition Detection
		The idea is to set an "open" flag in the position's transposition table element when the hash table is probed.
		The hash table element must be written when a node is entered, so an "always replace" scheme must be used.
		When a node is entered, the table is probed, if if the Zobrist key for the current position is in the table, a draw score is returned.
	www.seanet.com /~brucemo/topics/repetition.htm (1648 words)

	TRANS - transposing instrument
		underlined parameters are pfield-enabled for table or dynamic control (see the maketable or makeconnection scorefile commands).
		If updating transposition, work in linear octaves, and then convert to octave.pc before passing to the instrument.
		The table is expressed in linear octaves, then converted to octave.pc by the call to makeconverter.
	music.columbia.edu /cmc/RTcmix/docs/instruments/TRANS.html (486 words)

	Amirim Project Document
		The second fact to note about game-playing computer programs is the heavy use of transposition tables, which started as an improvement over Minimax (algorithm 4) but are nowadays also used as a data structure handling large databases of opening moves (in chess, for example) or tactical knowledge (like life and death tactics in Go).
		The natural conclusion is that transposition tables should store sets of position with each value instead of a single one; when a position is evaluated, the evaluation also gives us a set of other positions which are close enough to the original one.
		The definition of a good table is necessary for formally stating a correctness theorem for the algorithm (a similar definition was used in theorem 14).
	www.cs.huji.ac.il /~davidt/done/go/amirim_doc.html (9608 words)

	Aske Plaat: MTD(f), a new chess algorithm (Site not responding. Last check: 2007-10-10)
		The transposition table access code is the same as what is used in most tournament chess, checkers, and Othello programs.
		Therefore, to avoid any confusion, and even though the use of transposition tables is standard practice in the game playing community, the fact that MTD(f) needs a memory-enhanced searcher is stressed here.
		Note that you have to add the transposition table access code in the appropriate places yourself.
	theory.lcs.mit.edu /~plaat/mtdf.html (2811 words)

	RedHotPawn.com - Play free online chess
		A position is added to the table if there is no position currently held at its hash index.
		The Lock field of a table is used to verify that the position retrieved is the same as the position being evaluated in the search.
		The size of the hash table may be specified in kilobytes either on the command line or via the user interface.
	www.redhotpawn.com /rival/programming/transref.php (729 words)

	Retroviruses and yeast retrotransposons use overlapping sets of host genes -- Irwin et al. 15 (5): 641 -- Genome ...
		Based on GO functions, a subset of 66 genes identified in the current Ty3 screen representing nine categories from Table 1: stress/chaperone, cytoskeletal, vesicular/vacuolar, RNA processing, unknown, translation, Ty1 transposition repressors, nuclear transport, and DNA maintenance were chosen for analysis of transposition intermediates (Fun).
		Genes are colored according to function as indicated in the legend in functional groups corresponding to those in Table 1.
		ORFs encoding proteins that affected transposition were entered into GOnet, and interacting protein pairs as determined by all methods (synthetic lethal, two hybrid, and affinity purification) were downloaded for display in Cytoscape.
	www.genome.org /cgi/content/full/15/5/641 (7614 words)

	Tn7 recognizes transposition target structures associated with DNA replication using the DNA-binding protein TnsE -- ...
		in that transposition is not stimulated by replication of the
		Bainton, R.J., Kubo, K.M., Feng, J.-N., and Craig, N.L. Tn7 transposition: Target DNA recognition is mediated by multiple Tn7-encoded proteins in a purified in vitro system.
		Roberts, D., Hoopes, B.C., McClure, W.R., and Kleckner, N. IS10 transposition is regulated by DNA adenine methylation.
	www.genesdev.org /cgi/content/full/15/6/737 (6220 words)

	Transposition (Site not responding. Last check: 2007-10-10)
		For each number of halfsteps you want to transpose, there is more than one way the transpose and addtranspose parameters can be specified, as shown by this table.
		This allows to you control whether a sharp key or a flat key is to be used in cases where there is a choice.
		Another use for setting different transposition values is the following trick, useful in guitar music for printing both the real chords and chords for capo.
	www.arkkra.com /doc/uguide/trnspose.html (503 words)

	[No title]
		One option is to enlarge the hash table when the load factor becomes too large (typically larger than 0.75).
		Allocate a new table (typically at least twice as long as the old), then walk through all the items in the old table and _rehash_ them into the new.
		Take note: you CANNOT just copy the linked lists to the same buckets in the new table, because the hash functions of the two tables will certainly be incompatible.
	www.cs.berkeley.edu /~jrs/61bs02/lec/23 (552 words)

	The Left End of IS2: a Compromise between Transpositional Activity and an Essential Promoter Function That Regulates ...
		intermediate in the two-step transposition pathway of IS2.
		The five constructs shown are (see also Table 1) as follows: 1, pLL136; 2, pLL135; 3, pLL143; 4, pLL144; and 5, pLL146.
		Formation and transposition of the covalently closed IS30 circle: the relation between tandem dimers and monomeric circles.
	jb.asm.org /cgi/content/full/186/3/858 (4956 words)

	Recognizers and Transposition Tables (Site not responding. Last check: 2007-10-10)
		In this rather abstract respect recognizers resemble transposition tables which also serve as databases of search results and are found in all decent chess programs.
		Therefore, one must integrate recognizers with transposition tables if planning to augment the search by interior-node recognition.
		This greatly reduces the number of recognition trials whenever the rate of successful probes in the standard transposition tables is high (e.g.
	supertech.lcs.mit.edu /~heinz/dt/node37.html (251 words)

	Sequence and Positional Requirements for DNA Sites in a Mu Transpososome -- Goldhaber-Gordon et al. 277 (10): 7703 -- ... (Site not responding. Last check: 2007-10-10)
		Transposition Reactions-- Unless otherwise indicated, transposition reactions were done essentially as described (24), except that protein and DNA
		Transposition joints were specifically amplified with a pair of PCR primers, one to the target and one to
		transposition activity is due to MuA tetramers (5, 6).
	www.jbc.org /cgi/content/full/277/10/7703 (6770 words)

	Post-transcriptional Cosuppression of Ty1 Retrotransposition -- Garfinkel et al. 165 (1): 83 -- Genetics
		The Ty1-less strain DG1768 containing either pGTy1H3Neo or pGTy1H3 was induced for transposition and derivatives with 3 Ty1Neo, 10 Ty1Neo, 15 Ty1, or 20 (DG2451) additional Ty1 elements were recovered, as determined by Southern analysis (data not shown).
		The pGTy1 plasmids were transformed into a Ty1-less yeast strain carrying Ty1his3-AI(96) and initially tested for Ty1 transposition using a qualitative papillation assay as described in Fig 2.
		Transcriptional cosuppression shuts off Ty1 transcription in a subset of cells, while post-transcriptional cosuppression limits the action (represented by the X) of a stimulatory factor with Ty1 RNA in the rest of the cells.
	www.genetics.org /cgi/content/full/165/1/83 (7915 words)

	The Saccharomyces cerevisiae DNA Recombination and Repair Functions of the RAD52 Epistasis Group Inhibit Ty1 ...
		The plasmids utilized in this study are described in Table 1.
		transposition is elevated 5-fold in a rad54 mutant (Table 3).
		Ty1 transposition increased 38-fold in a cdc9-1 mutant (Table 3).
	www.genetics.org /cgi/content/full/154/2/543 (6077 words)

	Design and Implementation of a Simple Amazons Player
		By expressing board equality in terms of the graph isomorphism problem, the transposition table would need to store far fewer entries, particularly in the endgame.
		However, for efficient move generation queens should cause the line segments they lie on to be split, so that a list of valid half-moves may be generated simply by returning the list of squares appearing on line segments adjacent to the square being moved from.
		After further consideration, we remembered that graph isomorphism testing is expensive, and would be particularly impractical if applied to every board state ever compared against the transposition table.
	minilop.net /amazons/writeup.html (2786 words)

	Computer Chess Programming Theory
		The transposition table is a method of storing work which we have already done so that we don't have to do it again.
		The transposition table in chess engines work by creating a 'hash-value' for the current board position based on a random table of large integers.
		Internal iterative deepening is a method which can be used in conjunction with transposition tables, history heuristic and killer moves in order to improve your move ordering significantly.
	www.frayn.net /beowulf/theory.html (8273 words)

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