A Consideration On The Concepts Structure And Language- In Relation To Selections Of Translation Equivalents Of Verbs In Machine Translation System

To give appropriate translation equivalents for target words is one of the most fundamental problems in machine translation systrms. Especially, when the MT systems handle languages that have completely different structures like Japanese and European languages as source and target languages. In this report, we discuss about the data strucutre that enables appropriate selections of translation equivalents for verbs in the target language. This structure is based on the concepts strucutre with associated information relating source and target languages. Discussion have been made from the standpoint of realizability of the structure (e.g. from the standpoint of easiness of data collection and arrangement, easiness of realization and compactness of the size of storage space). i. Selection of Translation Equivalent Selection of translation equivalent of a verb becomes necessary when, (1) the verb has multiple meanings, or (2) the meaning of the verb is modified under different contexts (though it cannot be thought as multiple meanigns). For example, those words '?~ ', '~9~;~ ', '~< ', '~', ' r ~ ', '@~< ', ... are selectively used as translation equivalents of an English verb 'play' according as its context. i. play tennis : ~--~r~ 2. play in the ground : ~ ~ ~ ~"C~ 3. The children were playing ball (with each other) : -~/~,'--~rI~'g~t ~. play piano : ~'T~r~( 5. Lightning palyed across the sky as the storm began : ~ : ~ ~ f ~ h In the above examples, they are not essentially due to multiple meanigns of 'play' but need to assign different translation euqivalents according as the differences of contexts in the case of 1. to 3., and due to multiple meanings in the cases of 4. orS. A typical idea for selecting translation euqivalents so far is shown in the following example. Lets take a verb 'play'. If the object words of the verb belong to a category C play: ~ ~ obj we give a verb '?~ '(=do) as its appropriate translation equivalent. If the object words belong to a category CI~ : ~< , we give '~< ' as an appropriate translation equivalent of 'play'. Thus, we categories words (in the target language) that are agent, object, -." of a given verb (in the source language) according as differences of its appropriate translation equivalents. In other words, these words are categorized according as "such expression as a verb with its case filled with these words be afforded in the target language or not", and are by no means categorized by their concepts (meaning) alone. For example, for tennis, baseball, ... E CPobl~: S~ =(tennis, baseball, card, ...}, translation of 'play' are given as follows. play tennis : T--x~clt play baseball : ~ c i ~ play card : ~-F~c?" To the words belonging to C play: 9~ ( = obJ {piano, violine, harp, -.. ), the translation equivalent of 'play' is given as follows. play piano : ~'TJ ~z~< play violine : ~4 ~ i) ~r~ pla~ harp : ~" -/ ~r ~ < Categories given in this way have a problem that not a small part of them do not coincide with natural categories of concepts. For example, members ' 7 ~ (ten/lid) ' and ' ~(baseball) ' of a category belong to a natural category of concepts ~(ball game), but ' ~--Y(card)' does'nt. Instead it belorEs to a conceptual category ~ (game in general). ~ is considered as a sub-category of ~ . Therefore, if we regard C play: ~ ~ obJ as ~ , then ~---~ (tennis), ~-~" (card), 7 ~ ~ ~'--~ (football), ~7 (golf), --can be members of it, but ~(go), ~;~(shogi) which also belong to the conceptual category ~, are not appropriate as members of ~obl~ : $ ~ ('pl%y go : ~r~', 'play shogi : ~}~%~&' are not appropriate, instead we say 'pla~ go : ~r_~u _~ ', 'play shogi : ~_~._~') Therefore, cPla. y: $~ should be derided OD~ play" ~ & _~lay. ~ into two categories Cob j " and tobJ " @ The problem here is that, such division of categories do not necessarily coincide with natural division of conceptual categories. For