A Method for Distinguishing Exceptional and General Examples in Example-based Transfer Systems

A Method for Distinguishing Exceptional and G(m(.~L1 .... Examples-' ~ in Example-based Tr~msfer Systems Hideo W~tanal)c IBM th~search, Tokyo Research l,ahoratory 1623-14, Shimotsuruma, Yamatt)-shi, Kanagawa-ken 242, JAPAN e-malh watanahe~)trl.vrmt.lbm.com Abstract Distinguishing exceptional translation examples is an important issue in example-based transflw systems, because such systems use exceptional and general translation examples unifi)rmly. This l);qmr ,lescribes a mechanism for dealing with exc,q)tiomd transla- tion examples in our example-hosed tnLnsfer system, Sim~lban, and proposes a method for identifying such examples in a translation exampl~base. 1 Introduction and that we are given the folh)wing Japanese input s(,~.tence (sl): (sl) watashi(l)ha de,,t~ku(cah'ulator) w,, shiy- OIISH rll. In the almve exami,h~s , (s l) in likely to Im more sim- ilar to (,,1) than (e2), b,~c~use the three Japanese verbs "kyouyotmuru~" "tsakan," and "shiyousuru" are all w~ry simih~r, ~ and "dent~ku" ("calculator") is more similar to "konl)yuutaa" ("computer") than "kurum~'?' ("car"). If this is the case, the English out- put ohtained by using (el) is (tl),'-' whereas it should he 0,2): In recent years~ the example-based approach ha.s been used in many areas of natural language l)mcessing [3, 7, 8, 10~ 9, 1]. We haw~ been tlsing this al)- proach to develop a transfer system called 5'imTra', [13, 14, 16]. However, a bottleneck occured in the collection of large numbers of translathm examples consisting of pairs of parsed structures in the source and target languages (hereafter we (:all these struc- tures translation patterns)~ because parsing is not a perfi~et process. We now have some methods for over- coming this problem. For instance, recent studies [2, 11, 6, 12] have proposed mechanisms for collecting pairs of parsed structures automatically from transla- tion examples, and in the previous paper [15], 1 pro- posed ,~ method for extracting relevant translation patterns by comparing a wrong translation resttlL and its correct translation. Using these methods, we ca.n now collect translation patterns reh~tively easily. There is, however, another problem ca.lled e~:ample inte,¢e,~nce, wl,ich means that an ,xceptional (or id iomatie) translation pattern is selected when a gen- eral translation pattern should be selected; this has t~ side-effect on the construction of a target structure. Suppose that we have the following two translation examples from Japanese to English (el) and (e2), (el) watashi(1) ha konpyuuta~(computer) wo kyouy-- ollsllrll. I share the use of ~ computer. (e2) watashi(I) ha~ kurum~(ear) wo tsnkau. ]" /ISe a. car. (tl) I use the use of a calculator. (t2) I use a calculator. This probh~nl occurs because examph'~-ba,sed transfer systems choose examples simply on the basis of sim- ilarity. This ca.n be considered by using the analogy of cells like those shown in Figure 1. In the [igure, a dot represents a translation e×aml)le ~ and a cell rep- resents a spac(! in which an input is determined to be similar. According to this analogy, all example-blused system chex:ks the cell in which an input is located, ;~nd uses an ex~mple gow~rning the cell. If a new exa.mt)le is added in this space, it cell for …

Content truncated to 500 words