Topic: A Literature Review

There is a wide discussion for Chinese topic structure and topic-sentence acquisition in Second Language Acquisition since Li & Thompson (1976). This paper reviews the contribution made by Li & Thompson on topic and later researches on the basis of them. The relationship between subject and topic also is concentrated.

It is not necessary for topic to be the semantic argument of the predicate.
From the perspective of syntax: Topic is supposed to occur in the beginning of sentence; Generally, some pauses between topic and comment, or some topic marks, e.g. ne, ma, ba, ya.

From the perspective of pragmatic
Either definite or generic must be identified for the described matter by topic; The function of topic is to foreshow the topic centre, and set up the describing framework of comment For Chinese scholars, Zhang & Fang (1994) make a milestone for the study of topic in the background of functional linguistics. Such two researches found that the topic structure of Chinese is plentiful on the basis of oral Beijing dialect. They argue that Chinese is a kind of functional-focus language. It is suggested that the study of Chinese could benefit from the framework of Li & Thompson. But it is still insufficient to indicate the reality of Chinese. Actually, the framework of theme & rheme from the Prague school is recommended to take.
Nevertheless, the research of Zhang & Fang stems from the absolute oral language in which rely seriously on pause and tone particles of sentences. To some extent, it does not apply to the stylistic of written language. Besides, the analysis method of dynamic is negotiable. For this method, it is expected to analyze the sentences as per background and understanding of the researchers in the case of absence of topic remark. It may lead to various analysis results for the same sentence.

Topic study from the formal linguistics perspective
For the studies mentioned in the pervious section from the functional linguistics, they treat topic as the one of original sentence components. The topic can be existed without any transfer. This distinguishes from the view of theory of generative grammar, e.g. Huang (1982), A Li (1990) and Jiang (1992).
A tree-shape figure is produced to introduce the relevant definition: adjunction, it refers to a rule that some structure components are located in neighboring positions, and normally it is to use for the wh-movement in English.
From the figure 2, it can be seen that ZP move up to the front position of XP, and adjuncts in the front position of XP to be a sister-joint of XP from 2a to 2b. At the same time, during the process of adjunction, a new joint is created, namely XP2 (see figure 3). The original XP is named XP1(for a clear indication here, XP1 and XP2 are marked, or both are XP ). Both XP1 and ZP are under XP2. Hence, ZP transfers to be a adjunct component of co-referential with t.
Various adjunct relationships of figure 3 can be demonstrated in the following. Both of XP1 and XP2 are the maximum projection of X. XP1 can be defined the original maximum projection; XP2 governs XP1 and ZP; ZP is ruled by XP2, not ruled by XP1. That is to say, ZP partly lies in the range of X projection, which is one of adjunction. For YP, it distinguishes from ZP. YP is controlled by not only XP1 but also XP2. It can be concluded that YP is completely located in the range of X projection.
The attribute of ZP can be presented to be max.-projected by XP2, not ruled by XP1. Such attribute determinates that adjunction components are related to whole sentence, and seems to separate from main clause. For this phenomenon, Haegeman (1994) tropes that: for adjunction, a person is standing in the balcony. He is neither totally outside of the room, nor is totally inside. Therefore, for him, it is really easy to enter the room for discussion, and perhaps he is wetted by rain because of staying outside.
Following this contribution, a great number of studies under the framework of formal linguistics have occurred. J. Huang (1982) points out that the topic structure of Chinese is similar to the wh-structure of English. Both of these two are formed by movement. That is, J. Huang(1982) explains the topic structure of Chinese by wh-movement of English. Also he developed a framework of topic sentence (see figure 4).
From the figure 4, it shows that: after moving out from small sentence, TOP adjuncts on the left of the small sentence, and becomes a sister joint of S. At the same time, a new S joint occurs. Due to the fact the process can be produced, multiple topics in Chinese are expected to form. Both S and COMP are under S'. Lee (1986), Tang (1990) and Qu (1994) agree that topic is adjunction joints. As opposite to J. Huang (1982), they argue TOP is not result from movement whereas it is created in the basic position. Such argument is kind of same with functional linguistics. The topic structures offered by these researchers are similar expect some differences in terminologies. With the framework of Government Binding Theory, the work of Tang (1990) and Qu (1994) can be presented (see figure 5).
From the figure 5, it can be observed that Spec and IP are located in the under of CP from the low to the high, and then topic is formed on the basis of it that is a sister joint with CP. Eventually, one more CP joint comes out.
Nevertheless, under the framework of formal grammar, the topic studied by structure is much less comprehensive than functional grammar that is listing the topics one by one. Remarkably, with respect to exploration on the relation between topic and argument, it is much ambiguous. Therefore, Xu & Langendoen (1985) define the topic in combination with structure formula and depiction and the complicated analysis of Chinese topic structure: For structure formula [s' X[s…Y…]], X is a major syntax; Y may be treated as null element; and X and Y are related each other.
To some extent, Xu & Langendoen (1985) also state that topic is not led by movement. Furthermore, topic is supposed to be related to some position of the argument.

A quick comparison between functional linguistics and formal linguistics
Based on the discussion above, it is safe to say that the advantage for functional linguistics is more precisely, and the disadvantage is miscellaneous; for formal linguistics the advantage is succinct; the disadvantage is a weak rule for the relationship between topic and argument. Therefore, it can be benefited from the combination with these two perspectives. Such action will be helpful for a clear description of the topic.
The attributes of topic can be summarized in the following: Topic is NP in the beginning of sentence; It may pause or topic mark after topic; Topic must be either definite noun or generic noun; and It is possible for topic to not have selection relationship with verb in the sentence while it must have some relevant relation with argument.
Regarding the structure, Tang (1990) and Qu (1994) are suggested to be paid attention. Both of them claim that topic is a sister joint coming from basis foundation adhering on CP with maximum projection, and both of joints create a new CP joint (more details, see figure 5). Such structure may be more basic one, which is a part of initial state for Children learning first language.

Differences between topic and subject in Chinese
In the previous section, topic has been discussed from two perspectives of both functional linguistics and formal linguistics. In this section, the differences between topic and subject will be concentrated. On the one hand, subject is a definition that has been similar by most of people; on the other hand, such two elements are more likely to be confused. There are some arguments on the relationship between topic and subject since "topic" is introduced to the study of Chinese. Three significant arguments are listed as followed: Only subject, no topic in Chinese ; e.g. Lu (1979);Zhu (1982) and Lu (1986); Only topic, topic is equal to subject in Chinese; e.g. Zhao (1968); and Topic and subject co-exist in Chinese, belong to distinguishing grammar range; e.g. Li & Thomposn (1976); Cao (1997); Huang (1982); Li (1986); Tang (1990); and Qu (1994); Xu & Liu (1998); LY Shi (1998); YZ Shi (2001).
So far due to the fact that it is difficult to address some non-SVO standard sentence in Chinese, it is really rare for researchers to accept the previous two arguments. For the third one, there is an increasing trend in term of supports despite the existing of various definitions and descriptions on topic.
The argument on topic and subject in Chinese stems from that in some cases the noun at the beginning of sentence can be classified into either subject or topic, and it extremely clarifies them. The following sentence 2 and 3 can further demonstrate it: Sentence 2: (1) Xiao Zhang A, he will not come ( Subject and topic co-exist); (2) Xiao Zhang A, [ ] will not come (Only topic); (3) [ ], he will not come (Only subject);

Xiaozhang will not come.
It is obvious that there is a topic mark "A" in sentence 2 (2). If it is transferred into sentence 3, it will be hard to tell Xiao Zhang to be subject or topic. For such difficulty, some researchers have suggested to differentiate topic and topic in Chinese.

Li & Thompson -Various characteristics for topic and subject
Besides defining the topic, Li & Thompson (1976, 1981 identify the differences between topic and subject in term of characteristics: Topic is located at the beginning of sentence; Subject may be at the beginning, or in the middle of sentence; For topic, it may have special topic marker, e.g. "ne", "ma", "ba", "ya" after topic in spoken language; in the written language, coma after topic; and for it is not essential for subject; Topic always be "definite", and for subject is for "non-subject" (See sentence 4).
That book, I has returned to Xiao Ming already. (Definite for topic) One person is not able to eat 10 steam-bread. (Non-definite for subject) There is aboutness between topic and subject whereas there is selection relationship between subject and topic in term of semantic. That is, topic is supposed to be "doing/being" between topic and subject.

Liejiong Xu & Danqing Liu: differential structural poison for topic and subject
From the perspective of structure position, Xu & Liu (1998) classify the topic and subject. They propose a tree-shape figure by 4 various sentences (see figure 6).
They argue that NP1 in the location of Spec of TopcP (similar to CP structure from Tang (1990) and Qu (1994)) can be classified into topic while NP2 in the location of Spec of IP is regarded as subject. Hence, the essential difference for topic and subject in term of structure poison is:

Topic is inside of Topic P, and outside of IP; and for subject is inside of IP, outside of VP.
For the sentences in figure 6, they are featured into "the coincidence of subject & topic". That is to say, they are ambiguous from the perspective of syntactic whereas it is not ambiguous from the perspective of semantic because of same targets, and there is no trouble in understanding.
For the contribution in term of differentiating the topic and subject, some of researchers tend to classify the subject and topic from various layers. To some extent, topic is categorized into one definitions of pragmatic while for subject is semantic. It can not be denied that some differences exist between topic and subject. However, more attention should be given that topic plays a vital role from the perspective of semantic in topic-prominence and topic/subject prominence.
With reference to this argument, Xu & Liu (1998) state that there are two levels of meaning for topic: one is the syntactic topic which is overwhelmingly in topic-prominence and topic/subject prominence; another is that it apples to any kind of language as a topic with topic component of special topic function. For this paper, it is intended to the first level of meanings, namely, syntactic topic. To some extent, topic and subject are independent, which are separated syntactic element.
Nevertheless, the majority of Chinese researchers tend to achieve commonly: for one thing, it is not only topic but also subject in Chinese; for another thing, subject and topic are defined as distinguishing semantic components. However, it must be recognized that both subject and topic are coincident. More specifically, it can be understood that it is kind of intersection mathematically. Some parts are coincident while some are independent. To differentiate between subject and topic is still one of pending issues in the field of linguistics. But it is not the purpose of this paper.

Conclusion
Topic is one of significant issues in Chinese grammar. A detailed study can facilitate to analyze the basic structure of Chinese sentence as well as understanding the relationship between sentence structure and function. Besides this, it is related to word order of Chinese grammar. That is to say, it may clarify whether or how degree Chinese is classified into one type of SVO language. More importantly, it is also relevant to some common concerned, e.g. empty category; movement; and co-referential.   Xu & Liu (1996)