Dependency Relations
Core Arguments
What you’ll learn
- Tell a subject relation from an object relation at a glance
- Choose between attr, acomp and oprd for a word after a linking verb
- Know when an indirect object is dative and when it is prep plus pobj
- Tell ccomp from xcomp by asking whether the inner clause has its own subject
Required, not merely present
The test that separates this family from the rest is deletion. Marta repaired the radio quietly survives losing quietly — it just tells you less. It does not survive losing the radio: Marta repaired leaves you waiting for the rest of the sentence. The first is a modifier; the second is a core argument.
All thirteen share the same colour, because colour encodes the family and the label encodes the relation. Two red arcs in one tree are relatives, not duplicates.
Subjects
nsubjNominal subject
A noun or pronoun acting as the subject of a verb. Its head is the verb, and it is usually the first thing you can identify in a tree — find the root, then find what is doing it.
How spaCy decides: the nominal that agrees with the verb and, in a plain declarative, precedes it. Note the label attaches to the noun, never to the determiner in front of it.
“The lantern flickered twice.”
- detDeterminer
- nsubjNominal subject
- ROOTRoot of the sentence
- advmodAdverbial modifier
“She paints enormous murals.”
A sentence can carry several. An embedded clause has a subject of its own, and it is also nsubj — pointing at the embedded verb, not at the root.
“She hopes the rain stops.”
nsubjpassPassive nominal subject
The subject of a passive verb — grammatically the subject, but semantically the thing the action happened to. The bridge did not rebuild anything.
How spaCy decides: the subject of a verb that also has an auxpass child. The two labels travel together; seeing one without the other is a good sign the parse needs a look.
“The bridge was rebuilt.”
- detDeterminer
- nsubjpassPassive nominal subject
- auxpassPassive auxiliary
- ROOTRoot of the sentence
“Our tickets were refunded quickly.”
csubjClausal subject
A whole clause serving as the subject. The label goes on the verb of that inner clause, which is what makes it look strange at first — the arc runs verb-to-verb.
How spaCy decides: the root has no nominal subject of its own, and a subordinate verb occupies the slot where one would be. Rare in ordinary prose.
“Whoever wins gets the prize.”
- nsubjNominal subject
- csubjClausal subject
- ROOTRoot of the sentence
- detDeterminer
- dobjDirect object
“Whatever remains belongs to you.”
Objects
dobjDirect object
The direct object: the thing the verb acts on. Its head is the verb, and unlike a subject it normally follows.
How spaCy decides: a nominal after the verb that is not introduced by a preposition and is not the indirect object. In a two-object frame the second nominal is the dobj.
“Marta repaired the radio.”
- nsubjNominal subject
- ROOTRoot of the sentence
- detDeterminer
- dobjDirect object
“The waiter brought us coffee.”
“The noise startled him.”
dativeDative
The indirect object — the recipient — when it appears as a bare nominal directly after the verb.
How spaCy decides: position, essentially. In gave Nora the keys the first of two nominals is the dative.
“Rafael gave Nora the keys.”
- nsubjNominal subject
- ROOTRoot of the sentence
- dativeDative
- detDeterminer
- dobjDirect object
“Rafael handed the keys to Nora.”
Complements
Four labels compete for the slot after a verb, and choosing between them is the hardest part of this family. The deciding questions are: is the complement a noun or an adjective, and does it describe the subject or an object?
attrAttribute
A noun after a linking verb that renames the subject — the traditional predicate nominative. The winner and a stranger are the same person.
How spaCy decides: a nominal complement of a copular verb. Note this model makes be the root and hangs the complement off it — it does not use a separate copula relation.
“The winner was a stranger.”
- detDeterminer
- nsubjNominal subject
- ROOTRoot of the sentence
- attrAttribute
“This is my final offer.”
acompAdjectival complement
An adjective after a linking verb, describing the subject. Same slot as attr; the difference is purely the part of speech of the complement.
How spaCy decides: an adjectival complement of a verb. Comparatives behave identically to plain adjectives here.
“The pavement felt slippery.”
- detDeterminer
- nsubjNominal subject
- ROOTRoot of the sentence
- acompAdjectival complement
“The room grew darker.”
oprdObject predicate
An object predicate: a word describing the direct object rather than the subject. In elected him treasurer, treasurer is what him became.
How spaCy decides: this one is genuinely ambiguous, and Grammify has to resolve it. The label covers two different constructions, told apart by whether the verb has a direct object at all.
“The class elected him treasurer.”
- detDeterminer
- nsubjNominal subject
- ROOTRoot of the sentence
- dobjDirect object
- oprdObject predicate
“The evidence seems conclusive.”
ccompClausal complement
A clausal complement with its own subject — a whole clause functioning as the object of a verb of saying, thinking or asking.
How spaCy decides: the complement clause has a subject that is not shared with the outer verb. This is the one distinction that separates it from xcomp.
“He said the ferry sank.”
- nsubjNominal subject
- ROOTRoot of the sentence
- detDeterminer
- ccompClausal complement
“She asked whether anyone objected.”
xcompOpen clausal complement
An open clausal complement — one whose subject is missing and understood to be the outer clause’s. In Ravi wants to learn, the learner is Ravi, but nothing in the inner clause says so.
How spaCy decides: a complement clause with no subject of its own. “Open” means exactly that gap.
“Ravi wants to learn Portuguese.”
- nsubjNominal subject
- ROOTRoot of the sentence
- auxAuxiliary
- xcompOpen clausal complement
- dobjDirect object
“He seems to understand.”
Arguments of a preposition
pobjObject of preposition
The object of a preposition. Its head is always the preposition itself, never the verb or noun the phrase as a whole modifies — which is what makes a prepositional phrase two arcs rather than one.
The label sits on one word, the head noun: sofa, not the sofa. The phrase that word heads — it plus everything hanging below it — is what the Roles exercise boxes as the object of the preposition. The same holds for every relation on this page: nsubj marks keys, and the subject is The keys.
How spaCy decides: the nominal governed by a prep. It is one of the most frequent relations in the corpus, and it always appears alongside its preposition.
“The keys fell behind the sofa.”
- detDeterminer
- nsubjNominal subject
- ROOTRoot of the sentence
- prepPrepositional modifier
- pobjObject of preposition
“The road to Cusco reopened.”
pcompComplement of preposition
What a preposition takes when its complement is a clause rather than a plain noun — almost always an -ing form in English.
How spaCy decides: the complement of a preposition is verbal. Compare insisted on the delay (pobj) with insisted on leaving (pcomp).
“She insisted on leaving early.”
- nsubjNominal subject
- ROOTRoot of the sentence
- prepPrepositional modifier
- pcompComplement of preposition
- advmodAdverbial modifier
“They apologised for arriving late.”
agentAgent (passive)
The word by in a passive sentence, when it introduces the thing that actually performed the action. It is a special-cased preposition: the label sits on by itself, and the doer beneath it is an ordinary pobj.
How spaCy decides: by attached to a passive verb. An ordinary locative by — she waited by the door — stays a plain prep.
“The mural was painted by students.”
- detDeterminer
- nsubjpassPassive nominal subject
- auxpassPassive auxiliary
- ROOTRoot of the sentence
- agentAgent (passive)
- pobjObject of preposition
“The letter was signed by the mayor.”
- detDeterminer
- nsubjpassPassive nominal subject
- auxpassPassive auxiliary
- ROOTRoot of the sentence
- agentAgent (passive)
- pobjObject of preposition
Key terms
- Core argument
- Something a predicate requires rather than merely permits. Deleting it breaks the sentence instead of shortening it. Birds eat seeds. — drop seeds and the sentence breaks. She became a pilot.
See: Grammar Basics
- Complement
- A word or clause completing the meaning of a verb. Four labels share the slot:
attr,acomp,oprdand, for clauses,ccomp/xcomp. She became a pilot. —attr. The road was icy. —acomp. - Open clause
- A subordinate clause with no subject of its own, borrowing one from the clause above. The reason
xcompis called an open clausal complement. She wants to leave. — she is understood as the one leaving. They began to sing. - Indirect object
- The recipient. Labelled
dativewhen it is a bare nominal after the verb, butpreppluspobjwhen rephrased with to. She gave Luis a postcard. —dative. She gave a postcard to Luis. —prep+pobj.
Practice on a real sentence
nsubj and dobj; the xcomp is the one worth slowing down for.“John told the person being interviewed the reason for his unusual questions.”
Word dependencies
Pick a relation, click the head, then click the dependent.
Sentence — select a relation below, then click the words it connects
John told the person being interviewed the reason for his unusual questions.
Dependency tree — word-order columns
The dependency tree is built here as each relation is confirmed