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Topic: Backtracking

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	BtYacc: BackTracking Yacc
		BTYACC -- backtracking yacc =========================== BTYACC was created by Chris Dodd using ideas from many places and lots of code from the Berkeley Yacc distribution, which is a public domain yacc clone put together by the good folks at Berkeley.
		Version 1.0 changes: BackTracking ================================= by Chris Dodd BTYACC is a modified version of yacc that supports automatic backtracking and semantic disambiguation to parse ambiguous grammars, as well as syntactic sugar for inherited attributes (which tend to introduce conflicts).
		Backtracking is only triggered when the parse hits a shift/reduce or reduce/reduce conflict in the table.
	www.siber.com /btyacc (3112 words)

	Backtracking explained - Moritz Lenz
		Backtracking is the programmer's swiss army knife: Most problems where you can't find another solution for are solved by backtracking.
		A (only little) more advanced example is solving Sudokus using backtracking as implemented in YasSS, a Sudoku Solver.
		A very old (and often solved) Problem in computer science is how to place eight queens on a checkers board in a way that no queen can hit another one.
	moritz.faui2k3.org /en/backtracking (955 words)

	Backtracking
		Backtracking is a rather typical recursive algorithm, and any recursive algorithm can be rewritten as a stack algorithm.
		All of these versions of the backtracking algorithm are pretty simple, but when applied to a real problem, they can get pretty cluttered up with details.
		Notice that the backtracking altorithms require us to keep track, for each node on the current path, which of its children have been tried already (so we don't have to try them again).
	www.cis.upenn.edu /~matuszek/cit594-2002/Pages/backtracking.html (1582 words)

	Info Node: (elisp)Backtracking (Site not responding. Last check: )
		Note that backtracking is also reenabled automatically in several situations; it is reenabled when a new alternative is established by `andoptional', `andrest', or `andor', or at the start of processing a sublist, group, or indirect specification.
		The effect of enabling or disabling backtracking is limited to the remainder of the level currently being processed and lower levels.
		Backtracking is also disabled after successfully matching a quoted symbol or string specification, since this usually indicates a recognized construct.
	www.cs.cmu.edu /cgi-bin/info2www?(elisp)Backtracking (294 words)

	Backtracking Summary
		In backtracking, the solution to the problem is sought by finding a solution to one of the problems and then attempting to recursively solve the other sub-problems based on this initial solution.
		When backtracking is used in a constraint programming language, an added overhead occurs since information about the constraints, used by the constraint solver itself, needs to be updated as well.
		Backtracking is used in the implementation of programming languages (such as Planner and Prolog) and other areas such as text parsing.
	www.bookrags.com /Backtracking (1243 words)

	BACKTRACKING - Definition
		Backtracking terminates when there are no more solutions to the first sub-problem.
		An optimisation known as "intelligent backtracking" keeps track of the dependencies between sub-problems and only re-solves those which depend on an earlier solution which has changed.
		Backtracking is one algorithm which can be used to implement nondeterminism.
	www.hyperdictionary.com /dictionary/backtracking (163 words)

	Spartanburg SC \| GoUpstate.com \| Spartanburg Herald-Journal (Site not responding. Last check: )
		Backtracking is a type of algorithm that is a refinement of brute force search.
		This is usually achieved in a recursive function where each instance takes one more variable and alternatively assigns all the available values to it, keeping the one that is consistent with subsequent recursive calls.
		Another common use of backtracking is in Path Finding algorithms where the function traces over a graph of nodes and backtracks until it finds the least cost path.
	www.goupstate.com /apps/pbcs.dll/section?category=NEWS&template=wiki&text=backtracking (814 words)

	Sudoku Players' Forums :: View topic - Complexity, Trial & Error, Backtracking and Guessing
		I thought that backtracking is a systematic way of running through all possible candidate values in all cells.
		Backtracking has nothing to do with complexity, it is just one possibility of an algorithm.
		Backtracking can be done exponentially and polynomially, depending on the smartness of your algorithm.
	www.sudoku.com /forums/viewtopic.php?p=33016&sid=262763374340cb604acb504dcac79be9 (1542 words)

	Backtracking in Ptolemy II - Thomas Huining Feng (Site not responding. Last check: )
		This sub-project aims to develop an efficient incremental backtracking mechanism to be used in Ptolemy II.
		Backtracking is used here as a general term for the facility that takes the job of saving certain states of the system and restoring those states on request.
		Although on-the-fly backtracking is a challenging technique giving rise to some form of complication, it is well worth because of the performance gained.
	www.eecs.berkeley.edu /~tfeng/backtrack.html (2750 words)

	Info: (elisp) Backtracking (Site not responding. Last check: )
		Note that backtracking is also reenabled automatically in several situations; it is reenabled when a new alternative is established by `andoptional', `andrest', or `andor', or at the start of processing a sublist, group, or indirect specification.
		The effect of enabling or disabling backtracking is limited to the remainder of the level currently being processed and lower levels.
		Backtracking is also disabled after successfully matching a quoted symbol or string specification, since this usually indicates a recognized construct.
	www.cit.gu.edu.au /teaching/2105CIT/cgi-bin/info2html.cgi?(elisp)Backtracking (294 words)

	Info: (lispref) Backtracking (Site not responding. Last check: )
		Backtracking is disabled for the remainder of a sublist or group when certain conditions occur, described below.
		Backtracking is reenabled when a new alternative is established by `andoptional', `andrest', or `andor'.
		Second, backtracking is disabled after successfully matching a quoted symbol or string specification, since this usually indicates a recognized construct.
	www.cit.gu.edu.au /teaching/2105CIT/cgi-bin/info2html.cgi?(lispref)Backtracking (265 words)

	BL: Backtracking (Site not responding. Last check: )
		Employed Backtracking Techniques: Briefly, the algorithm conceptually explores a binary tree top-to-bottom; however, at any time the data structures represent a simple path from the root down to the current active node in the tree.
		During general backtracking, a set that was previously included is then considered for exclusion.
		A backtrack is I) a decision to exclude a previously included set, or II) a decision that a set cannot be excluded because it is an essential set, or III) a decision to back up to the previous level in the decision tree.
	www.cs.unm.edu /~bill/studies/bktkpage (999 words)

	XEmacs Lisp Reference Manual - Backtracking
		Backtracking is disabled for the remainder of a sublist or group when certain conditions occur, described below.
		Backtracking is reenabled when a new alternative is established by
		Second, backtracking is disabled after successfully matching a quoted symbol or string specification, since this usually indicates a recognized construct.
	www.tau.ac.il /cc/pages/docs/xemacs/lispref_257.html (275 words)

	Constraint Guide - Systematic Search
		Backtracking incrementally attempts to extend a partial solution that specifies consistent values for some of the variables, toward a complete solution, by repeatedly choosing a value for another variable consistent with the values in the current partial solution.
		Backtracking can be seen as a merge of generate and test phases from the GT approach.
		Even if the conflicting values of variables is identified during the intelligent backtracking, they are not remembered for immediate detection of the same conflict in a subsequent computation.
	ktiml.mff.cuni.cz /~bartak/constraints/backtrack.html (604 words)

	backtracking from FOLDOC (Site not responding. Last check: )
		Backtracking terminates when there are no more solutions to the first sub-problem.
		An optimisation known as "intelligent backtracking" keeps track of the dependencies between sub-problems and only re-solves those which depend on an earlier solution which has changed.
		Backtracking is one algorithm which can be used to implement nondeterminism.
	www.instantweb.com /foldoc/foldoc.cgi?backtracking (190 words)

	Dr. Dobb's \| Solving Combinatorial Problems with STL and Backtracking \| April 15, 2003
		Backtracking is part of a family of related algorithms: branch-and-bound, hill-climbing, Z, A, alpha-beta search, etc., all which use general problem solving techniques to solve combinatorial problems.
		The backtrack algorithm continues to traverse the tree, descending level by level as long as the coloring is valid, and backtracking and pruning as soon as it detects an invalid coloring.
		BackTrack's operator() takes the begin and end iterators to your container, along with a bool parameter that specifies whether this is the first call.
	www.ddj.com /dept/cpp/184401194?pgno=2 (2923 words)

	Backtracking and Constraints in Tcl-BC
		Backtracking as a mathematical concept predates electronic computers by at least 60 years [Lucas, 1891] and is, of course, widely used as a programming technique in artificial intelligence and operations research [see, for example, Schalkoff, 1990].
		Backtracking allows the choices to be made, in some sequence, and with each choice, the computation proceeds, until "failure" (presumed lack of viability of the choice) is encountered.
		Backtracking has some of the flavor of setjmp/longjmp, but for a number of reasons, not the least of which is the fact that choice points may occur within procedures whose activation has ended, it involves a more complicated state restoration/preservation.
	www.usenix.org /publications/library/proceedings/tcl96/full_papers/clark/index.html (4907 words)

	Algebra Session 6: Solving Equations
		Backtracking involves "undoing" operations to work backwards from the output to the input.
		Think about whether a function machine's operation could always be "undone." You might also look for problems in Part C that would be difficult to solve by backtracking.
		A similar problem appears in Session 2, Part B. If you find a formula for the number of toothpicks at a given stage, you can backtrack using that formula.
	www.learner.org /channel/courses/learningmath/algebra/session6/part_b/backtracking.html (710 words)

	Memory Management in And-Parallelism
		Backtracking is not anymore a continuous activity, but is a sequence of sequential steps performed by different agents, with all the expenses incurred to ensure a proper synchronization and transfer of control.
		The main disadvantage of public backtracking is the inability of performing garbage collection on the fly during backtracking--clearly an agent cannot recover memory belonging to another agent
		This has the considerable advantage that, once the backtracking point has been detected, the set of bindings to be removed can be obtained in a single step--this thanks to the fact that a single piece of information is sufficient to detect the set of conditional bindings to remove.
	www.cs.nmsu.edu /~epontell/adventure/node45.html (1811 words)

	Backtracking Intrusions
		The goal of backtracking is to identify automatically potential sequence of steps that occurred in an intrusion.Back tracking identifies files and processes that could have affected that detection point and displays the chain of events in a dependency graph.we use backtracker to analyse several real attacks against computers that we set up as honeypots.
		There are numerous ways to detect a compromise occurred on a system.such as trip wire which can detect modified system files, fire wall can detect a process conducting a port scan or launching a service attack,sand boxing tool can notice a program making disallowed or unusual patterns of system calls.
		Backtracker works backwards from a detection point and identifies chain of events could have led to modifications that was detected.In order to identify these chain of events,back tracker logs the system calls that induce most directly dependencies between operating system objects(i.e creating a process and writing files)
	www.clarkson.edu /projects/itl/honeypot/Backtracking.html (951 words)

	Backtracking Algorithm
		Allen [2] was the first to propose that a backtracking algorithm [11] could be used to find a consistent scenario of an IA network.
		To test whether an instantiation of a variable is consistent with instantiations of past variables and with possible instantiations of future variables, we use an incremental path consistency algorithm (in Step 1 of Figure 3 instead of initializing L to be all edges, it is initialized to the single edge that has changed).
		After backtracking completes, a solution of the SA network can be found using a fast algorithm given by van Beek [25].
	www.cs.washington.edu /research/jair/volume4/vanbeek96a-html/node6.html (2336 words)

	Backtracking
		Backtracking is a systematic method for generating all (or subsets of) combinortial objects.
		When we backtrack to the root, the whole tree has been fully generated, and the algorithm stops.
		Therefore, Backtracking is never applied to generate all objects for large object sizes.
	www.seas.gwu.edu /~ayoussef/cs212/backtracking.html (1506 words)

	Kelbt: Backtracking LR Parsing (Site not responding. Last check: )
		First, it elevates backtracking to the level of semantic actions by introducing a class of actions called undo actions.
		Undo actions are invoked as the backtracker undoes parsing and allow the user to revert any side effects of forward semantic actions.
		As a proof of concept, Kelbt has been used to write a partial C++ parser (included) which is composed of strictly a scanner, a name lookup stage and a grammar with standard semantic actions and semantic undo actions.
	www.cs.queensu.ca /home/thurston/kelbt (321 words)

	Figure 2 : Backtracking by single RNA polymerase molecules observed at near-base-pair resolution : Nature
		Backtracking occurs upon entry into long, but not short, pauses.
		Backtracking by single RNA polymerase molecules observed at near-base-pair resolution
		The three phases of motion are indicated below the trace: phase 1 (backtracking, solid line), phase 2 (pause, dotted line), and phase 3 (recovery, solid line).
	www.nature.com /nature/journal/v426/n6967/fig_tab/nature02191_F2.html (190 words)

	Constraint Guide - Constraint Propagation
		As a skeleton we use the simple backtracking algorithm that incrementally instantiates variables and extends a partial solution that specifies consistent values for some of the variables, toward a complete solution, by repeatedly choosing a value for another variable.
		Even simple backtracking (BT) performs some kind of consistency technique and it can be seen as a combination of pure generate and test and a fraction of arc consistency.
		The BT algorithm can be easily extended to backtrack to the conflicting variable and, thus, to incorporate some form of look-back scheme or intelligent backtracking.
	ktiml.mff.cuni.cz /~bartak/constraints/propagation.html (715 words)

	RE: [xri] Decision on Ref "backtracking" issue
		I do not think we should be backtracking through all levels of a QXRI.
		If that REF was unavailable then we would need to try the next REF. I-Name: =les.chasen -----Original Message----- From: Wachob, Gabe [mailto:gwachob@visa.com] Sent: Monday, January 23, 2006 4:46 PM To: Steven Churchill; drummond.reed@cordance.net; xri@lists.oasis-open.org Cc: drummond.reed@gmail.com Subject: RE: [xri] Decision on Ref "backtracking" issue Steve- I understand the need for a stack.
		I still think that "backtracking" up that stack (er, down the stack, depending on how you draw it) adds complexity - I'd rather say that if you get stuck somewhere, that you don't even bother unwinding the stack to a decision point and try something else.
	www.oasis-open.org /archives/xri/200601/msg00064.html (986 words)

	backtracking spoofed packets
		This survey and backtracking analysis at Oak Ridge National Laboratory is sponsored by the Office of Counter Intelligence of the US Departmant of Energy.
		Since the source addresses are spoofed, it is impossible to know what the real source of the packets is without backtracking an active flow.
		There have also been several backtracking papers (master's thesis) on using active networks to backtrack and block spoofed attack flows.
	www.csm.ornl.gov /~dunigan/oci/bktrk.html (1112 words)

	Solving Soduku Using Backtracking :: Scratch Projects
		Description: We will use a simple backtracking algorithm to quickly solve a Soduku puzzle.
		This article will try to give a useful example in recursive programming and in backtracking algorithms in general.
		Fill in a 9x9 grid in such the numbers 1 through 9 appear only once in each row and each column, and only once in 9 3x3 sub grids on the game board.
	www.scratchprojects.com /2006/04/solving_soduku_using_backtracking_p01.php (436 words)

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