Zero

零，零形式

A term used in some areas of linguistics to refer to an abstract unit postulated by an analysis, but which has no physical realization in the stream of speech. Its symbol is Ø. In English morphology, for example, the pressure of the grammatical system to analyse plurals as Noun + plural has led some linguists to analyse unchanged nouns, such as sheep and deer, as Noun + plural also, the plurality in these cases being realized as zero (a zero morph). A ‘zero operation’ of this kind is also called an ‘identity operation’, one where the input and the output of the operation are identical. Similarly, in other grammatical contexts where a given morpheme usually occurs, the absence of that morpheme under certain conditions may be referred to as zero, e.g. zero infinitive, referring to the absence of to before the verb in English; zero article, referring to the absence of a definite or indefinite article before a noun; zero connectors, as in he said he was coming, where that is omitted; zero valency, referring in valency grammar to verbs which take no complements; and zero relative clauses, as in the book I bought ... In cases such as He’s laughing, is he, some linguists analyse the second part of the sentence as a reduced form of the verb phrase is he laughing, referring to the omitted part by the term zero anaphora. Zero is also found in phonological analysis, e.g. in a conception of some types of juncture as zero phonemes, or to suggest a structural parallelism between syllable types (a CV sequence being seen as a CVC sequence, with the final C is being zero).

Zero is especially encountered in the formulation of generative rules, where the term refers to an item deleted from a given context (a ‘deletion rule’). Such rules are of the type ‘rewrite A as zero, in the context X -Y’ (A→Ø / X - Y), and they apply in grammar, semantics and phonology. In X-bar syntax, a zero-level or zero-bar category is a lexical category.

It is plain that the introduction of zero (sometimes referred to as the null element, deriving from the use of this term in mathematics) is motivated by the need to maintain a proportionality, or regular pattern, in one’s analysis, or in the interests of devising an economic statement. It should also be noted that too many zeros in an analysis weaken its plausibility.

语言学某些领域用来指一种分析法设定的一个抽象单位，但在语流中没有任何有形的实现。使用的符号是Ø。例如英语形态学，由于语法系统要求将复数都分析为名词+复数，有的语言学家在分析不变形名词如sheep“羊”和deer“鹿”时也将其分析为名词+复数，只是这里的复数实现为零（零语子）。这种“零形操作”也称作“等同操作”，即操作的输入和输出等同。同样，其他语法上下文中如果通常有一给定语素出现，在某些条件下它的不出现就称作零形式，例如零形不定式是指英语不定式动词前没有to；零形冠词是指一个名词前没有定冠词或不定冠词；零形连接成分是指he said he was coming“他说他就来”这类句子中省略的that；零价是配价语法指不带任何补语的动词；零形关系小句是指省略关系代词的关系小句，如the book I bought ...“我买的书…”。在He’s laughing, is he“他在大笑，是不是”这类句子中，有的语言学家将句子的后半部分分析为动词短语is he laughing“他是不是在大笑”的缩减形式，并将缩减的部分称作零形复指。音系学的分析也利用零形式，例如将某些类型的音渡视作零音位，或在不同音节类型之间建立结构上的平行关系（一个CV序列可视为CVC序列，最后的C为零）。

零特别见于生成规则的形式表述，指在给定上下文中删除的一个项目（“删除规则”的作用）。这类规则术语在“X - Y的上下文中重写A为零”一类（A→Ø / X - Y），对语法、语义学和音系学都适用。在X-杠句法中，零层面或零杠语类是词汇语类。

引入零的概念（有时称作null（空）成分，借用自数学）目的是为了在某种分析中保持均衡性成对称性，或是为了作出较经济的说明。但分析中引入太多的零会削弱分析的合理性。