Structural-semantic classification of the predicate in sentence in Modern English

3.2.4 Prepositions

Prepositions, such as “with”, “of”, “for”, and “from” are words that relate two nouns or a noun and a verb. Prepositions require a noun phrase argument (to form a prepositional phrase). It is estimated that there about 150 different prepositions (including 94 one-word prepositions and 56 complex prepositions, such as “out of”)^[14]. Prepositions are generally considered a closed class, but the possibility of complex combinations suggests that algorithms might be better off allowing for out of vocabulary examples.

3.2.5 Adjectives and Adverbs

Adjectives normally modify nouns, as in “the big red book”, but may also be an argument of a verb (including forms of “be”, “feel”, “appear”, and “become”). Adjectives can also be marked as comparative (meaning “more than typical”, using the suffix “-er”) or superlative (meaning “more than any others”, using the suffix “-est”). Adverbs modify verbs, adjectives, or other adverbs. They express manner or intensity. They may be comparative (e.g., “better”) or superlative (e.g., “best”). Adverbs that end in the suffix “-ly” have been derived from a related adjective (e.g., “quickly“ is derived from “quick“).

3.2.6 Conjunctions

Conjunctions, such as “and”, “although”, “because”, “but”, “however”, “or”, “nor”, “so”, “unless”, “when”, “where”, “while”, etc. are words that join words, phrases, clauses, or sentences. They can be discontinuous, e.g,. “either … or”, “neither … nor”, “both … and”, “not only … but also”, “on the one hand … on the other (hand)”, “not just … but”, and “not only … but”. They can take modifiers, such as “particularly”, as in Figure 3.6.

Figure 3.6 Example of a modified conjunction

These have been among the country’s leading imports, particularly last year when there were shortages that led many traders to buy heavily and pay dearly. [wsj 1469]

There are three major types of conjunctions: coordinating conjunctions, subordinating conjunctions, and correlative conjunctions. A coordinating conjunction (e.g., “and”, “but”, “or”, and “so”) joins two structures that have the same type. Their purpose is to express that two entities did something together, or two events happened at the same time. A subordinating conjunction (e.g., “after”, “although”, “because”, “before”, “if”, “how”, “however”, “since”, “once”, “until”, “when”, “where”, “while”, “whenever”, “as soon as”, “even if”, “no matter how”, etc) join a subordinate (dependent) and a main (independent) clause. The main clause can be understood on its own. The dependent clause can only be fully understood in the context of the main clause, as its purpose is to provide background, explanation, justification, or possible exceptions to what is said in the main clause. Thus, they express what is known as rhetorical structure or discourse relations among clauses, which can occur either within the same sentence or between adjacent sentences. When they link adjacent sentences at the sentence level, these words function as adverbs, so subordinating conjunctions are often labelled as adverbs, wherever they occur, and some experts refer to them as conjunctive adverbs. Sometimes subordinating conjunctions are labelled as prepositions, as in the Penn Treebank II. Discourse relations can exist without any explicit conjunction, but by using hand-annotated data, such as the Penn Discourse Treebank or the Biomedical Discourse Relation Bank, they can be identified using automated discourse parsing. A correlative conjunction is a discontinuous conjunction that joins words, phrases, or clauses that have a complementary relationship. Because they are discontinuous, they are harder to learn, and so automated systems do not always label them consistently. Figure 3.7 includes some sentences illustrating different types of conjunctions and how they are labelled using the default Stanford CoreNLP part-of-speech tagger.

Figure 3.7 Examples of conjunctions
Example sentences	Type of expression with labels given by CoreNLP
You can walk but you cannot run.	Coordinating conjunction, labelled as conjunction
You can read at home or in the library.	Coordinating conjunction, labelled as conjunction
My daughter and her friends like to climb.	Coordinating conjunction, labelled as conjunction
My cat purrs when you pet her.	Subordinating conjunction, labelled as adverb
If you study hard, you will do well.	Subordinating conjunction, labelled as preposition
You can either walk or take the bus.	Correlative conjunction, labelled as adverb, conjunction
The car not only is quiet but also handles well.	Correlative conjunction, labelled adverb, adverb, conjunction, adverb
Embryonic Stem cells have a high mitotic index and form colonies. So, experiments can be completed rapidly and easily.	Discourse adverbial, labelled as adverb
Obese cats have higher levels of inflammatory chemicals in their bloodstream. However, rapid shifts in fat tissue further increase this inflammation.	Discourse adverbial, labelled as adverb