Topic Systems In Text

The issue of topic systems in text arises from a theoretical hypothesis thatHalliday's category of Theme be largely a formal, syntactic concept, while thedue semantic counterpart be Topic, aboutness of a piece of messageextending the area of the clause, clause complex, paragraph, section, chapter,book, or a text as a whole. The topics thus formed interweave into sets ofconstellation, which further display hierarchical statuses.(i) At the clause rank, topics are assigned with the function for demandingcomments. The relation is comparatively an unmarked but structural one, butnot without variation since in some cases comments would precede topics.This dynamic nature will become more salient when simultaneouslyconfigured with prominent interpersonal features, e.g. the so-called EnhancedThematic Structures. Meanwhile, a background topic has an immediateresponsibility for what to come in the remainder of the clause.(ii) For the clause complex, there may occur more than one topic. Thesetopics are attributed with statuses of different importance, such as Primary,Secondary, Tertiary, and so on. But the nature of status assignment maymerely bear local significance since some are very important throughout thesurrounding contexts. Such relations are still within the domain of structurality,but the dynamic, organisitional feature is obvious because their structuralcharacteristic is only confined to the general syntacticality. In fact, somesecondary, tertiary or other downgraded topics may even appear before theirprimaries.(iii) An entire dynamicality of topic relationship is associated with those areasbeyond the clause complex, where the repetitions of various topics in textconstitute constellations of networks;and the meronomic, collective, andhyponymic specifications of the non-repetitive topics, i.e. parts, individuals,and hyponyms, diffuse respectively around their corresponding general,leading entities, i.e. the whole, collection, and superordinate topics. Moreover,there may also be Possessive and Additional chains from every now and then.As for contrastive parallels, "fronting" becomes an unmarked phenomenon,through which the orgnisational feature is most remarkably manifested.(iv) These topics of the various relations may be so complicated thathierarchies emerge for their interpretations. That is, some chains are morecentral while others are just peripheral. Of course, some central topics aremerely locally defined, and beyond would proceed more significant ones forthe holistic central concern of a text. This is the Downward type of the localcentral. But some are immediate to their surrounding contexts, which is calledthe Upward type. However, the demarcation of the local and the holistic is onlyextremity. In fact, chains of intermediate length are common. Of course thismodel also goes to the local and the holistic marginal topics.(v) Central and marginal topic chains may signal straightforward identificationof central and marginal stretches of text, the latter two of which may in turn betaken into account for figuring out the main concern(s) of a text as a wholefrom the perspective of text summarisation. Actually, the hierarchical systemsof text stretches as well as the hierarchical topic systems may be regarded asclues for the gist of a text. Hence, such an endeavour would result inadvances for computational generalisation or summarisation.(vi) Meanwhile, the observation of the encoder's intention is noticed as aproblem of the discrepancy between the titles, subheads, and central topics,and what the writer really intends to convey. In fact, one intention may directlybe expressed over another. But linguistic clues may help display theencoder's true intention(s). Furthermore, pragmatic strategies and principlesare always alive in the realisation process. They work as the basis on whichmetaphorisation and topicalisation take place. And lastly, the complicatedsequential phenomena of topic development require a great deal of cognitiveprocessing effort.(vii) Along the analyses, schematic attempts have been made forprogramming topics of various kinds for recognition and generation on thecomputer. Incidentally, there have already been some works that could beemployed as the databases, such as the WordNet by Princeton University.And the Computational Linguistics Studies Centre in Peking University isexploring an English-Chinese version of the WordNet system. What is needednow is technical work to fill the gap for their ultimate realisation.(viii) Furthermore, topicalisation realises the situational parameter Mode, thespeaker's manipulative ways of arrangements of experiential meaning interms of his cognitive schema and communicative intention in aware of theaddressee's knowledge;and the phonological category for realising Topic andTheme is Tonicity.It is then clear that topic systems in text are informational in essence. Eachtype of topic system has been figured out as it is for message transaction.Meanwhile, its relation with Thematisation – the corresponding formalcounterpart – has also been pointed out in available places. Main points, suchas exhaustive explications of topic systems with other textual categories, anda new model of language, have been laid out for further studies.To sum up, this thesis started with verifying the formal nature of Theme in theclassical SFL, and pointed out Topic as the semantic counterpart. On thisbasis, it surveyed the studies of topic so far, and worked out an overallframework for what has been done and what not in the literature in question,which unified 'sentence topic' and 'discourse topic' as an integrated whole.This process has witnessed a systematic analysis of these issues and madean attempt for the programming. Finally, an implication was made for a newmap of language. Therefore, the attempt has not only theoretical significance,but is also contributive for Text Linguistics or Discourse Analysis.