Semantic Roles and Argument Structure › Predicates and Their Arguments

In the analysis used here, a predicate denotes a property or relation applied to its arguments. Carve denotes a relation between a carver and something carved. Give denotes a three-way relation among a giver, a gift, and a recipient. Rain denotes a zero-place relation: something happens, but nothing is required to participate.

The contrast between a thing and a relation is the first conceptual step. In the illustrated sentences, the noun phrases the roast and the chef refer to entities. In that verbal use, carve relates a carver to an entity being carved. You cannot understand the meaning of carve without understanding that it brings participants with it. Think of carve as having slots for the carver and the thing carved.

The slots a predicate opens are filled by arguments.

Predicatehood depends on how an expression is used. In "the hammer broke the window", the hammer fills a participant slot of broke. In "she hammered the nail flat", hammered is a verbal predicate. These related forms have different jobs; their spelling alone is insufficient to identify the predicate-argument structure.

Whether an expression is annotated as a predicate depends on its use and the chosen predicate inventory. Nouns can also organize participant structure. In "the attack on the city", nominal attack names an event and relates it to its target, the city. Naming an event does not make the noun nonpredicative.

Arguments are not always noun phrases. They can be clauses ("She believes that he left"), infinitives ("She wants to leave"), or prepositional phrases ("She put the book on the table"). Some subjects are not semantic arguments at all: in "It is raining", the it is a pleonastic placeholder with no referent, and in "There is a book on the table" the there is an expletive. A role labeler that assigns an Agent role to expletive it has misunderstood the syntax.

The variety of argument forms is one reason SRL is harder than it first appears. A system cannot simply look for noun phrases to the left and right of a verb. It has to recognize that a whole clause can fill a slot, that an infinitive can fill a slot, and that a prepositional phrase can fill a slot. It also has to recognize when a grammatical subject is not a participant in the event at all. A subject-to-Agent shortcut would fail on these expletive examples: their subject position does not establish an event participant.

Not every phrase in a clause fills a participant slot selected by the verb. Compare:

• "She put the book on the table."
• "She read the book on the table."

Both contain a PP headed by on. In the ordinary placement reading, "She put the book" leaves the selected location unspecified and is incomplete without supporting context. "She read the book" is acceptable without a location. On the event-location reading used here, the PP is an argument of put and an adjunct of read; the second sentence also permits a different attachment, identifying the book on the table (Merlo, 2003, Section 3).

Linguists use several diagnostics to separate the two:

• Omissibility. A selected phrase may resist omission, as in the ordinary placement reading of "She put the book on the table" versus "*She put the book". Other arguments can be implicit, so omission alone does not settle argumenthood.
• Entailment. "She put the book on the table" entails that the book ended up on the table. In "She read the book on the table", the PP also permits attachment to book, describing which book was read. On an event-modifier reading, it adds a location that read itself does not select; the example does not establish the book's location is unconstrained.
• Iterability. Merlo contrasts "*Chris rented the gazebo to girls, to boys" with "Kim met Sandy in Baltimore in the hotel lobby in a corner" (2003, Section 3). The first is marked unacceptable as an iteration of the selected recipient; the second accumulates locative modifiers. Such contrasts are diagnostic evidence under the intended interpretations, rather than a rule that every repeated PP is unacceptable.
• Lexical sensitivity. The same PP can be an argument for one verb and an adjunct for another, as the put/read pair shows.
• Do-so substitution. In "She read the book in the library, and he did so at home", the location can remain outside the material replaced by did so. Such stranding has been used as an argumenthood diagnostic, but its interpretation is contested; it is not a categorical test (McInnerney, 2024).

Each diagnostic targets a different symptom, and no single diagnostic is decisive in every case. Omissibility asks whether the sentence remains grammatical without the phrase. The entailment cue asks whether the intended verb sense includes a participant of the kind expressed by the phrase. Iterability asks whether the phrase behaves like a modifier that can be repeated. Lexical sensitivity asks whether the phrase's status depends on the verb. The do-so example asks which material the pro-form can replace while leaving a modifier outside it. Agreement among tests supplies evidence for an analysis, but the existing tests and test collections discussed by Kim et al. do not supply necessary and sufficient conditions for every dependent (Kim et al., 2019, Section 2). Conflicting results should be recorded rather than forced into a supposedly decisive test.

The diagnostics are easier to compare side by side. The chart below scores four phrases from the put/read and give/cook contrasts on three tests. The scores are schematic illustration only: they are hand-assigned and are not measured annotation data. In the transfer reading of give, the entailment mark concerns the recipient slot. The phrase to the guest identifies who receives the item, and the recipient can remain implicit in a suitable context.

The contrast concerns lexical selection, not just whether a phrase is spoken. The cooking example can omit its kitchen location. The transfer reading of give includes a recipient even when context leaves that participant unexpressed. An annotation inventory then makes its own distinctions: a numbered argument or an AM label is a resource convention, not a numerical measurement of argumenthood.

Annotation conventions must be read separately from these linguistic diagnostics. PropBank defines numbered roles in predicate-specific framesets and general modifier labels such as AM-LOC and AM-TMP. Its original specification explicitly avoids committing to a strict linguistic argument/adjunct division: some phrases that a linguistic analysis might call adjuncts receive numbered roles. NEG and MOD are also represented among the general labels without being ordinary adjuncts (Palmer et al., 2005, Section 3). A labeler must follow the chosen resource's definitions rather than infer the label solely from omissibility.

Here valency describes how many semantic participants a predicate sense selects and what kinds they are.

For the senses illustrated here, rain has no participant argument, sleep one, devour two, and give three. In “She slept,” she is the only participant counted under the bare intransitive reading. These are analyses of particular predicate senses, not immutable counts attached to a spelling. A trivalent transfer reading distinguishes giver, transferred item, and recipient even when context leaves a participant implicit.

Here valency counts semantic participants. Subcategorization records their syntactic realization; other descriptions also use valency for syntactic dependents, so the counting convention must be stated.

The distinction between valency and subcategorization is the distinction between how many participants there are and how those participants are expressed. A verb can be trivalent and still permit more than one frame, because the same three participants can be arranged syntactically in more than one way. Conversely, two verbs can have the same valency and permit different frames. A lexicon or model needs to account for both the participant structure and the permitted syntactic patterns.

In the transfer sense of give, the giver is the subject in both examples. The postverbal complements can follow either pattern, [NP NP] or [NP PP_to]:

• "She gave the student a book." (double object)
• "She gave a book to the student." (prepositional dative)

In the standard-English pattern illustrated here, explain permits "She explained the rule to the student", while "She explained the student the rule" is marked unacceptable. This is a restriction on that verb and variety, rather than a universal test of a speaker's language competence. Similar broad transfer meanings do not guarantee identical syntactic frames; a computational lexicon or learned model must represent the permitted realizations.

The two verbs can both be described broadly in terms of transfer, but that description leaves out lexical distinctions relevant to their realizations. The example therefore does not prove that syntax is independent of meaning or that a learner must memorize every frame separately. It shows what a lexicon or model must distinguish in this variety. In cross-language work, check the realizations licensed by the translated predicate rather than copying an English frame.

English has systematic diathesis alternations that change how a predicate's participants are expressed. Four examples show why grammatical position alone cannot identify a semantic role.

Here an alternation is a pair of related realization patterns. Passive voice can rearrange the same expressed participants; the causative/inchoative pair below contrasts a clause that names the causer with one that describes the change alone. The examples are evidence against identifying subject with Agent or object with Patient, rather than a claim that every alternation preserves full meaning.

Passive. "The chef carved the roast" becomes "The roast was carved by the chef." The active direct object the roast becomes the passive subject. The active subject the chef appears inside an optional by-phrase.

The passive illustrates the distinction between syntax and semantic roles. The two sentences can describe the same event with the same participants and roles. In the passive, was is the auxiliary and carved is the participle, spelled the same as the active past tense. The preposition by introduces the carver in this example. A rule that labels every subject as Agent would mislabel the roast in this passive example.

Dative shift. "She gave a book to the student" becomes "She gave the student a book." The recipient moves from a PP into the first object slot.

In both variants, the student is the recipient and the book is the thing given. The double-object variant places the recipient immediately after the verb as a bare noun phrase. The prepositional dative expresses the same recipient inside a to-phrase. In the double-object example, labeling the first object Patient would misidentify the recipient. The verb sense and the construction give the evidence for the role assignment.

Causative/inchoative. "The chef melted the butter" becomes "The butter melted." The inchoative makes the affected entity the subject without naming a cause.

The causative/inchoative alternation is a small lesson in event structure. The transitive variant describes an event with a causer and an affected entity. The intransitive variant describes the butter changing state and leaves open what caused the change. The butter is the patient in both cases, even though it is the object in one sentence and the subject in the other. This is another clear case where grammatical relation and semantic role come apart.

Spray/load. "She sprayed paint on the wall" becomes "She sprayed the wall with paint." The direct object switches from the substance being moved to the surface receiving it.

The spray/load alternation supplies another contrast between grammatical relations and participant roles. In one variant the direct object is the material; in the other it is the location. The direct-object label alone does not say whether paint or wall fills the material role.

The spray/load pair is worth pausing over because it defeats several simple heuristics at once. The verb is the same. The participants are the same. The preposition changes, and the direct object changes. A rule that always labels the first postverbal NP Material would label the paint correctly in the first variant and mislabel the wall in the second. A model that learns "the noun phrase after with is the instrument" will also fail, because in "sprayed the wall with paint", the with-phrase is not an instrument. The paint is the material, and the wall is the surface. An analysis that needs to preserve the material/surface distinction must represent it somewhere, rather than derive it from the preposition alone.

Three constructions show why restricting the target to simple verbal predicates leaves important analysis choices unresolved.

Light verbs and support constructions. In "take a shower", "make a decision", or "give a talk", the noun names the event. Annotation schemes vary in whether they treat the noun or the verb as the predicate.

A support construction need not use the ordinary lexical sense of its verb. FrameNet analyzes "Pa gave her a lecture" with lecture as the frame-evoking target and gave as a support verb; Pa is Speaker and her is Addressee (FrameNet II, Section 3.1). Treating this as an ordinary transfer of a lecture would miss that annotation target. Other schemes may represent the construction differently, so predicate identification must follow the selected scheme.

Nominal predicates. "The army's destruction of the city" has the same participant structure as "The army destroyed the city", but the predicate is a noun. PropBank includes nominal framesets, and FrameNet includes nouns as lexical units. An extractor restricted to verbs would miss the destruction relation in this example.

A second example places event descriptions inside noun phrases. A sentence like "The committee's approval of the proposal led to immediate funding" contains two event-like nouns, approval and funding, each with its own participant structure. A verb-only extractor sees only led and misses the approval relation entirely. Including these nouns in the annotation target makes their participant relations available to the extractor; this example does not measure the added coverage or prediction difficulty.

Constructions. Goldberg (1995) analyzes caused motion as a construction pairing a subject, a nonstative verb, a direct object, and a directional phrase with a causal-motion interpretation. "Pat sneezed the napkin off the table" adapts her example, with the prepositional phrase off the table giving the direction. In this analysis, participant structure comes from combining the verb with the caused-motion construction; it is not projected from sneeze alone.

Compare the intransitive "Pat sneezed" with the caused-motion sentence. In the intransitive example, the selected core participant is the sneezer. PropBank's sneeze.01 likewise lists only ARG0, the person sneezing (complete frame file); that is a resource-specific role inventory, not a frequency claim about every use of the verb. In Goldberg's constructional analysis, the napkin realizes the entity caused to move and off the table expresses its path. The sentence means roughly "Pat caused the napkin to move off the table by sneezing". Sneezing supplies the means of causing the motion, while the caused-motion construction supplies the causal-motion structure. This illustrates a construction-based account in which a grammatical pattern pairs form with meaning.