The terminology used to denote arguments and adjuncts can vary depending on the theory at hand.
Some dependency grammars, for instance, employ the term circonstant (instead of adjunct), following Tesnière (1959).
The area of grammar that explores the nature of predicates, their arguments, and adjuncts is called valency theory.
Predicates have valency; they determine the number and type of arguments that can or must appear in their environment.
Take the sentence John helped Bill in Central Park on Sunday as an example: An adverbial adjunct is a sentence element that often establishes the circumstances in which the action or state expressed by the verb takes place.
Adjuncts that modify adjectives and adverbs are occasionally called adadjectival and adadverbial.
Adjuncts can be categorized in terms of the functional meaning that they contribute to the phrase, clause, or sentence in which they appear.
E.g.: Further diagnostics used to distinguish between arguments and adjuncts include multiplicity, distance from head, and the ability to coordinate.
This fact bears witness to the difficulty of providing an absolute diagnostic for the distinctions currently being examined.
Such examples illustrate that distinguishing predicates, arguments, and adjuncts can become difficult and there are many cases where a given expression functions in more ways than one.
Many theories of syntax and grammar employ trees to represent the structure of sentences.
Theories that assume sentence structure to be less layered than the analyses just given sometimes employ a special convention to distinguish adjuncts from arguments.
The standard, non-arrow dependency edges identify Sam, Susan, that very long story that you like, etc.