Lauri Karttunen and Martin Kay. Structure sharing with binary trees. In Proceedings of the 23rd Annual Meeting of the Association for Computational Linguistics (ACL-85) [1], pages 133-136A.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....DG node to another; arc bindings that add to a node a new arc. Lazy Copying as another method to achieve structure sharing is based on the idea of lazy evaluation. Copying is delayed until a destructive change is about to happen. Lazy copying to achieve structure sharing has been suggested by [Karttunen Kay 85] and lately again by [Godden 901 and [Kogure 901. Neither of these methods fully avoids redundant copying in cases when we have to copy a node that is not the root. In general, all nodes along the path leading from the root to the site of an update need to be copied as well, even if they are not ....

....SharedArcs2 DO unify(SharedArcl.dest,SharedArc2.dest) return(node) END unify Figure 4: The unification procedure 328 approach methods early over redundant incr. lazy structure copying copying copying copying copying sharing naive yes yes yes no no no Peteira 85 no no no no no yes Karttunen Kay 85 no no yes no yes yes Karttunen 86 no no yes no no no Wroblewski 87 no yes yes yes no no Godden 90 no no yes no yes yes Kogure 90 no yes yes no yes yes LIC no yes no yes yes yes Figure 5: Comparison of unification approaches Both of these approaches suffer from difficulties of their own. In ....

Lauri Karttunen and Martin Kay. Structure sharing with binary trees. In Proceedings of the 23 r Annual Meeting of the Association for Computational Linguistics, ACL, pp. 133-136a, Chicago, IL, 1985.

....the two values do not match then the unification fails immediately. The unification is a very important process in any parser. Even we have used in our application one of the most efficient algorithms, we are currently testing another dag representation which uses binary trees and lazy evaluation [17] (the dags in that representation also shares structures and allow an efficient duplication) This representation does not use an environment structure and therefore may be more appropriate to our application. Anyway, no comparisons are yet available. The initial project included a minimal ....

Karttunen, L., Kay, M., - "Structure Sharing with Binary Trees" in More Notes from the Unification Underground - A Second Compilation of Papers on Unification-Based Grammar Formalisms, SRI International, 1985.

....und Technologie) under grant No. 08 B3116 3. The views and conclusions contained herein are those of the authors and should not be interpreted as representing official policies. DG copying as a source of inefficiency Previous research on unification, in particular on graph unification [Karttunen Kay 85, Pereira 85] and others, identified DG copying as the main source of inefficiency. The high cost in terms of time spent for copying and in terms of space required for the copies themselves accounts for a significant amount of the total processing time. Actually, more time is spent for copying ....

....DG node to another; arc bindings that add to a node a new arc. Lazy Copying as another method to achieve structure sharing is based on the idea of lazy evaluation. Copying is delayed until a destructive change is about to happen. Lazy copying to achieve structure sharing has been suggested by [Karttunen Kay 85] and lately again by [Godden 90] and [Kogure 90] Neither of these methods fully avoids redundant copying in cases when we have to copy a node that is not the root. In general, all nodes along the path leading from the root to the site of an update need to be copied as well, even if they are not ....

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Lauri Karttunen and Martin Kay. Structure sharing with binary trees. In Proceedings of the 23 rd Annual Meeting of the Association for Computational Linguistics, ACL, pp. 133--136a, Chicago, IL, 1985.

....making the text easier to understand, and less prone to incorrect interpretation. A typical application area is one in which the correct execution of a procedure manipulating objects in the domain is safety (or legally) critical, e.g. AECMA89] 3 Previous Work Previous work in this are includes [KK85] and [Per85] The work described in [Per85] is particularly interesting and relevant to that described here. Direct analogies can be drawn between solutions to various sub problems and to allow for comparison a summary of [Per85] follows. The underlying observations, motivation and concepts map ....

Lauri Kaurttunen and Martin Kay. Structure sharing with binary trees. In 23rd Annual Meeting of the Association of Computational Linguistics. ACL, 1985.

....general case of the problem. Pugh [8] states that the theoretical properties of lazy structure sharing are not well understood. Indeed, while lazy structure sharing has been used to implement unification of first order terms [3] theorem provers [2, 6] and computational linguistics applications [4, 5, 7], almost all of these works provide only empirical (if any) observations about its effects. Only Cordin and Bidoit [3] provide any asymptotic analysis of the effect of lazy structure sharing; they consider a variant similar to our total order strategy (see below) We are thus motivated to consider ....

L. Karttunen and M. Kay. Structure sharing with binary trees. In Proc. 23rd Ann. Mtg. of the Asso. for Computation Linguistics, pages 133--6a, 1985.

....a description of the changes ( deltas ) it wants applied to the forest. This allows us to code the system more cleanly and opens some interesting avenues for parallelization in the system. Previous work in the area of structure sharing in natural language parsers include that of Karttunen and Kay ([KK85]) and Pereira ( Per85] Karttunen s work, in particular, provides us with two key ideas utilized in the current proposal, relative addressing and lazy copying. Section 2 briefly explains the representation of compact forests as output by Tomita s algorithm. Section 3 discusses some benefits of ....

....node s location. In the case of our above example, the relative address would be Go up one node, then take the leftmost branch down (to reach the A node) then take the leftmost branch down (to reach the proper governor) A similar relative addressing scheme was devised by Karttunen and Kay (see [KK85]) but AP A A 1 AP A A AP Spec (governed by both A1 A2) 2 Figure 4: Relative addressing preserves structure sharing. wasn t used for this exact purpose in their system. We adopt their relative addressing idea to preserve our structure sharing and extend it to allow for node packing. In our ....

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Lauri Karttunen and Martin Kay. Structure Sharing with Binary Trees. In Proceedings of the 23rd Annual Meeting of the ACL. Association for Computational Linguistics, 1985.

....structures. One approach to this problem is to refine parsing algorithms by developing techniques such as restrictions, structure sharing, and lazy unification that reduce the amount of structure that is stored and hence the need for copying of features structures (Shieber, 1985; Pereira, 1985; Karttunen and Kay, 1985; Wroblewski, 1987; Gerdemann, 1989; Godden, 1990; Kogure, 1990; Emele, 1991; Tomabechi, 1991; Harrison and Ellison, 1992) While these techniques can yield significant improvements in performance, the generality of unification based grammar formalisms means that there are still cases where ....

L. Karttunen and M. Kay. 1985. Structure sharing with binary trees. In 23 th meeting Assoc.

....overall savings. However, experiments in which all common structure was shared as in Figure 1 suggest that maximizing structure sharing would further improve performance. This structure sharing approach is based on much previous work in optimizing Feature Structure based parsing. See for example, Karttunen 1985 and Pereira 1985) 4 The LCA Preserving Algorithms 4.1 The Maximal Tree Alignment Problem A formal definition of the alignment problem corresponds closely to that found in Matsumoto et al. 1993. The algorithm finds a maximum score correspondence between nodes in a pair of parse trees. We begin ....

Karttunen, Lauri. 1985. Structure-Sharing with Binary Trees. In Proceedings of the 23rd Annual Meeting of the Association for Computational Linguistics.

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Lauri Karttunen and Martin Kay. Structure sharing with binary trees. In Proceedings of the 23rd Annual Meeting of the Association for Computational Linguistics (ACL-85) [1], pages 133-136A.

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Lauri Karttunen. 1985. Structure-Sharing with Binary Trees. In Proceedings of the 23rd Annual Meeting of the Association for Computational Linguistics.

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