Extracting Nested Collocations

Extracting Nested Collocations Katerina T. Frantzi and Sophia Ananiadou Dept. of ()omputing Manch(;sl;(;r Metroi)olil;an Univ(;rsity Manchester, MI 5G]), U.K. {K.Frantzi,S.Ananiadou}(~(toc.mmu.a(:.uk Abstract 'l?his paper 1)rovidcs an at)l)roa(:h to tim semi-aul;onmtic exl;i'action of (:olloca- IJons flom eorl)ora using sl;atisti(:s. The growing availability of lm'ge textual cor- t)ora, and the in(:reasing number of ap- plications of colloeal;ion extra(:tion, has given risc~ 1;o wu.ious apt)roaches on the I;opi(:. In l;his palter, we address the probl(;m of 'ne,stcd collocrd, ions; thai, is, those being l)art of longer colloc;ttions. Most approa(:hes till now, tl'(!al;ed sub- st;rings of collo(:at;ions as eollocal;ions, only if they apl)eared ffequenl;ly enough 1)y l;hemselves in the cor[)llS. 'Fhese tech- niques le['l; ~r lot; of collocations mmx- l;ra(:l;ed, in this 1)ai)er, we i)rol)oSe an al- goril;hln for a semi-aul;oma|;ic exl;ra(;l;ion of nesl;ed uninl;errupl;ed anti inl;errul)l;ed collo(:al;iolls, paying parl;icular al;l;(~lll;ion to nested collocat;ion. 1 Introduction Tim increased inl;erest in collocation ext;raetion comes from t;hu faeI; l;hal, t;hey can be used for many NLP at)plical;ions such as machine transla- (;ion, maehilw, aids R)r t;ra.nslal,ion, dictionary con- sl;ru(:i;ion, and secon(1 language learning, t.o mmm a few. Recently, large scale textual corpora give the potential of working with the real data, (!ither fin' grammar inferring, or for enriching the le.x- icon. These corlms-based at)preaches have also been used for the extract, ion of collocal,ions. In this t)al)er we are concerned wil;h nested collocations. Collocations Lhat are subst;rings of oLher longer ones. I{egar(ling l;his l;ypu of (:olloea- tion, the approaches till ilOW could be divi(led inl;o t;wo groups: those thai; do uo(, refer to s'ttbstrings of colloco, l, ions as a l)arti(:ular problem, (Church and lla.nks, t99(); Kim and Cho, 1993; Nagao and Mori, 1994), and those t.hat; do (Kita et al., t994; Smadja, 1993; lkchara et al., 1995; Kjelhner, 11994). [towew;r, (well the lal;t, er, deal wiLh only 1)arl; of the probh;m: they l,ry not to extract the mlwanl;cd substrings of collocations. In favour of this, l;hcy leave a large number of nested colloc.a- tions unextracted. ht section 2 collocations arc briefly discussed and the. l)roblem is determined. In section 3 our approach to t;he probl0an, 1;he algorithm and an examl)le are given. In section d the experimeld, S are discussed and t;he Inethod is (;olnpare(t with t, hat proposed by (Kita et a.l., 199d). In sectioll 5 I;tlel'e are conlmenl;s on relal;ed work and tinally Section 6 eonl;ains I;he conc, hlsions and 1;he fill;life work. 2 Collocations - The Problem Collocations are perwtsive in language: "letters" are "deliw:red", "tea" is "strong" and not "pow- elful", we "l'mt progrants", aitd so Oll. Linguists have long been interested in collocations and the detinitions are nuiaerous and varied. Some re- searchers include multi-o.leinent eOlnpOuIlds as (;x- amples of collocations; some admit only collo- cations (:onsisl;ing of pairs of words, while oth- ers admit only eollo(;ations consisting of a max- imum of tive or six words; some emphasize syn- l, aglnat, ic aspecl;s, others Selnmtl;ic aspects. The COlllillOil poini;s regarding collocations appear to be, as (Smadja, 1993) suggestsl: they are …

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