Syntax (linguistics): rules and structure of sentences

The place of syntax in grammar

In terms of natural languages, syntax is a department of grammar and closely adjacent to morphology. The distinction between them refers to levels of complexity of the grammatical structure of linguistic expressions. For example: From the minimal linguistic sign (morpheme) frag as the root of a word via the extended form by adding the prefix be to the word form befragst, morphology is responsible. From there on the levels of complexity upwards, i.e. from the syntagm ask the candidate via the simple sentence (if) you ask the candidate to the compound sentence hold back if you ask the candidate, syntax is responsible. For syntax, the word-form is a whole with whose inner structure syntactic rules have nothing to do; these only have to "know" which syntactically relevant morphological categories the word-form belongs to in the first place. Thus, for example, a syntactic rule determines that the predicate verb in wenn du den Kandidaten befragst is in congruence with its subject in the second person singular. But what this form is (for this verb) is a matter of morphology (e.g. if the verb were hereinlässt, it would - in contrast to befragst - have an umlaut).

The problems of demarcation between syntax and morphology can be gauged, among other things, by phrasal compounds such as hinuntergehen (one or two words?) or reitende Artillerietruppe (the attribute reitend belongs to artillery, which, however, is itself a component of another word). Derivation, which belongs to morphology as part of word formation, also has a syntactic aspect.

Sentence syntax, word syntax, text syntax

In the conventional sense, syntax means the study of the sentence (i.e. the study of correct sentence structure) or the sentence structure itself. Syntax, as part of grammar, deals with the patterns and rules by which words are assembled into larger functional units, such as the sentence just mentioned, and relationships such as part-whole, dependency, etc. are formulated between these sentence elements.

Apart from this sentence-centered perspective (sentence syntax, sentence syntax), one also speaks in a broader sense of intraverbal syntax or word syntax (also: word syntax or morphotactics), which studies combinatory rules in morphology, and of text syntax (text syntax), which deals with the rules of combining sentences into texts. The use of the word syntax, in which syntax is coextensive with grammar (i.e., either includes morphology or ascribes it to phonology), is found primarily in English-language linguistics and in the theory of formal languages (in which morphology plays no role).

Theories of sentence syntax

In general linguistics, there is a variety and competition of syntax models, theories and schools. "Each of the models presented has its strengths and weaknesses." In addition to the models of traditional school grammar, syntax is studied in terms of hypothesized universal innate form principles (Noam Chomsky) or its communicative purpose (functional syntax) or its role in the construction of complex meanings (logical semantics, Montague or categorical grammar). Numerous such models are listed in the article Syntax theory. Among the more important ones are:

• the dependency grammar
• the Government and Binding theory (Chomsky 1981), a variant of generative grammar
• the Head-driven Phrase Structure Grammar.

The syntactic structure of a natural language sentence is represented differently in these models. The variants of the phrase structure grammar represent it in the form of a structure tree, which graphically represents the part-whole relationships of the constituents of the sentence. The dependency grammar represents it in the form of a stemma, which shows the dependencies between words.

The syntax of a formal language (formal syntax) - such as calculi in logic and mathematics or programming languages in computer science - is a system of rules according to which well-formed ("syntactically correct") expressions, formulas, program texts or other texts are formed from a basic set of characters (the alphabet). The rules can have the form of derivation rules of a formal grammar or be formulated in natural language.

If only well-formedness or correctness is concerned, the meaning of the content of the signs can be disregarded. If, however, semantics is to be defined on the well-formed expressions, this is usually done inductively on the basis of the same rules by which syntax is defined, so that the meaning of a complex expression results from the meaning of its constituent parts and the rule for composition (Frege's principle). For example, in the language definition of programming languages, the priority of operators is reflected in the formal grammar of the language, so that according to its syntactic rules, an expression such as can only be read as a sum, not as a product. For mere well-formedness, this would not have mattered.

The programming language Algol 60 was the first to be described with a formal syntax written in the Backus-Naur form (BNF; named after two of the authors of the language definition). Since then, formal syntax descriptions have become generally accepted for programming languages, namely with the help of various versions and extensions of the BNF or of syntax diagrams, not least because analysis programs (parsers) can be generated automatically from the formal rules under certain conditions. As a consequence, the syntax of a programming language is often understood to mean only these rules, but not those syntax rules that cannot be expressed by context-free grammars, such as the obligation to declare occurring names.

In the XML markup language, there is a syntax that is valid for all documents, which is further restricted by additional syntax rules depending on the area of application. Conformity with the general syntax is called well-formedness, and conformity with the additional rules is called validity.