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This page pertains to UD version 2.

Complex Clauses


Complex clauses involving coordination arise when two main clauses or two subordinate clauses at the same level are linked in a coordinate structure, which may or may not involve an overt coordinating conjunction. We treat coordinate structures asymmetrically by taking the first conjunct as the head with all other conjuncts attached to it via the u-dep/conj relation. Coordinating conjunctions and punctuation delimiting the conjuncts are attached to the immediately following conjunct using the u-dep/cc and u-dep/punct relations respectively.

He came home , took a shower and immediately went to bed .
conj(came, took)
conj(came, went)
punct(took, ,-4)
cc(went, and)

Asyndetic coordination occurs when there is no overt coordinating conjunction.

Veni , vidi , vici .
conj(Veni, vidi)
conj(Veni, vici)
punct(vidi, ,-2)
punct(vici, ,-4)

As a special case, the first conjunct may be implicit or part of an earlier sentence.

And then we left .
cc(left, And)

Ellipsis in Clause Coordination

Coordination is often combined with ellipsis, where one or more of the normally obligatory constituents of a clause or omitted because they can be inferred from material in another conjunct.

If the main predicate is elided, an associated aux or cop can be promoted to head of the clause.

Sue likes pasta and Peter does , too . 

nsubj(likes-2, Sue-1)
obj(likes-2, pasta-3)
conj(likes-2, does-6)
nsubj(does-6, Peter-5)
advmod(does-6, too-8)
Sue is hungry and Peter is , too . 

nsubj(hungry-3, Sue-1)
cop(hungry-3, is-2)
conj(hungry-3, is-6)
nsubj(is-6, Peter-5)
advmod(is-6, too-8)

In more complicated cases where a predicate is elided but no aux or cop is present, promotion can lead to unnatural and confusing relations. For example, in the following sentence, you would be the subject of coffee, suggesting that the second clause contains a nonverbal predication rather than an elided predicate.

I like tea and you coffee .

nsubj(like-2, I-1)
obj(like-2, tea-3)
nsubj(coffee-6, you-5)
conj(like-2, coffee-6)

In such cases, we therefore use the special orphan relation to attach siblings to the promoted element.

I like tea and you coffee .

nsubj(like-2, I-1)
obj(like-2, tea-3)
conj(like-2, you-5)
cc(you-5, and-4)
orphan(you-5, coffee-6)
Mary wants to buy a book and Jenny a CD .

nsubj(wants-2, Mary-1)
xcomp(wants-2, buy-4)
obj(buy-4, book-6)
conj(wants-2, Jenny-8)
orphan(Jenny-8, CD-10)
They had left the company , many for good .

nsubj(left, They)
obj(left, company)
conj(left, many)
orphan(many, good)
Mary wants to buy a book . ROOT And Jenny a CD .

nsubj(wants-2, Mary-1)
xcomp(wants-2, buy-4)
obj(buy-4, book-6)
root(ROOT, Jenny)
orphan(Jenny, CD)

Note that the orphan relation is only used when an ordinary relation would be misleading (for example, when attaching an object to a subject). In particular, the ordinary cc relation should be used for the coordinating conjunction, which attaches to the pseudo-constituent formed through the orphan dependency.


Complex clauses involving subordination arise because a core or non-core dependent is realized as a clausal structure. We distinguish four basic types:

  1. Clausal subjects (u-dep/csubj).
  2. Clausal complements (objects), divided into those with obligatory control (u-dep/xcomp) and those without (u-dep/ccomp).
  3. Adverbial clause modifiers (u-dep/advcl).
  4. Adnominal clause modifiers (u-dep/acl) (with relative clauses as an important subtype in many languages).

In addition, we discuss secondary predicates, which are analyzed as clausal complements or adnominal clause modifiers.

Clausal Subjects

A clausal subject is a clausal syntactic subject of a clause. Its governor may be a verb or a nonverbal predicate. If the governor is in the passive, the subtype csubj:pass can be used.

What she said makes sense
csubj(makes, said)
What she said is interesting
csubj(interesting, said)
What she said was well received
csubj:pass(received, said)

Clausal Complements (Objects)

A clausal complement of a verb or adjective is a dependent clause which is a core argument. That is, it functions like an object of the verb, or adjective.

He says that you like to swim
ccomp(says, like)
mark(like, that)
He says you like to swim
ccomp(says, like)

Such clausal complements may be finite or nonfinite. However, if the subject of the clausal complement is controlled (that is, must be the same as the higher subject or object, with no other possible interpretation), the appropriate relation is xcomp.

The boss said to start digging
ccomp(said, start)
mark(start, to)
xcomp(start, digging)
We started digging
xcomp(started, digging)

The key difference here is that, in the first sentence, who will be starting to do the digging is a question of anaphora (it may be some contextually relevant individual or group, which may or may not include the boss), while in both sentences, the person or persons who are starting to do something are necessarily the same people who are digging (i.e., in the second sentence, the subject of digging can only be we). This is what distinguishes ccomp and xcomp.

The controlled subject of the xcomp can also be an obj – indeed, it is usually the obj when one is present (Visser’s generalization). UD adopts an object with infinitive (or “raising to object”) analysis of such constructions (rather than the “small clause” or “exceptional case marking” analyses that are prominent in many recent strands of generative grammar). So UD uses analyses like the following for cases where there is obligatory control between an object and the subject of a subordinate clause:

Sue persuaded Fred to accept the job.
obj(persuaded, Fred)
mark(accept, to)
xcomp(persuaded, accept)
Please let us know
discourse(let, Please)
obj(let, us)
xcomp(let, know)

Finally, ccomp is used with copulas in equational constructions involving full clauses.

The important thing is to keep calm.
ccomp(is, keep)
nsubj(is, thing)
The problem is that this has never been tried .
ccomp(is, tried)
nsubj(is, problem)

(In these cases, the copula is treated as a head to preserve the integrity of clause boundaries and prevent one predicate to be assigned two subjects. This is not an optimal solution given the analysis of equational constructions involving nominals, where one of the nominals is treated as the head, but it is the preferred solution for now.)

Adverbial Clause Modifiers

An adverbial clause modifier is a clause which modifies a verb or other predicate (adjective, etc.), as a modifier not as a core complement. This includes things such as a temporal clause, consequence, conditional clause, purpose clause, etc. The dependent must be clausal (or else it is an advmod) and the dependent is the main predicate of the clause.

The accident happened as night was falling
advcl(happened, falling)
If you know who did it, you should tell the teacher
advcl(tell, know)
He talked to him in order to secure the account
advcl(talked, secure)
He was upset when I talked to him
advcl(upset, talked)

Adnominal Clause Modifiers

An adnominal clause modifier is a clause which modifies a nominal.

the issues as he sees them
acl(issues, sees)
Cette affaire à suivre \n This case to follow 
acl(affaire, suivre)

This relation is also used for optional depictives. The adjective is taken to modify the nominal of which it provides a secondary predication.

She entered the room sad
acl(She, sad)
He painted the model naked
acl(model, naked)

A relative clause is a special type of adnominal clause, characterized by finiteness and usually omission of the modified noun in the embedded clause. Some languages use a language-particular subtype for the traditional class of relative clauses.

I saw the man you love
acl(man, love)

Some languages allow finite clausal complements for nouns with a subset of nouns like fact or report. These look roughly like relative clauses, but do not have any omitted role in the dependent clause. This is the class of “content clauses” in Huddleston and Pullum 2002). These are also analyzed as acl.

the fact that nobody cares
acl(fact, cares)

Secondary Predicates

A clause can contain a secondary predication or predicative. The most common case is with adjectives, although the same effect can sometimes be achieved with a predicative noun or preposition-marked phrase.

There are two predicates in such sentences, the main predicate and an additional one, such as the cake being beatiful or She being sad.

Huddleston and Pullum (2002) “The Cambridge Grammar of the English Language”, chapter 4 section 5.3, divide predicatives into obligatory and optional predicatives, which can be either depictives or resultatives, and which can appear in an intransitive or transitive clause, giving eight possibilities:

In UD, obligatory predicatives are always treated as an xcomp: The secondary predicate is attached as an xcomp of the main predicate. In most cases, as well as an adjective depictive, you can use a verbal or nominal predicate in the same position (e.g., He looked [an idiot]; This made me [seethe with anger]).

She declared the cake beautiful .
nsubj(declared, She)
obj(declared, cake)
xcomp(declared, beautiful)

In the enhanced representation, there is an additional subject link showing the secondary predication, which is obligatorily a particular role in the higher clause:

She declared the cake beautiful .
nsubj(declared, She)
obj(declared, cake)
xcomp(declared, beautiful)
nsubj(beautiful, cake)

A Czech example:

jmenovat někoho generálem \n to-appoint someone as-a-general
obj(jmenovat, někoho)
xcomp(jmenovat, generálem)

The relation xcomp is used for core arguments of clausal predicates, so it will not be used for some other instances of secondary predication. Optional depictives are analyzed as adjuncts, and made the acl of the nominal that they semantically modify (if one is present).

For instance, in She entered the room sad we also have a double predication (she entered the room; she was sad). But sad is not a core argument of enter: leaving it out will neither affect grammaticality nor significantly alter the meaning of the verb. On the other hand, leaving out beautiful in She declared the cake beautiful will either render the sentence ungrammatical or lead to a different interpretation of declared.

The result is that in She entered the room sad, sad will depend on She and the relation will be acl instead of xcomp:

She entered the room sad .
obj(entered, room)
acl(She, sad)
He painted the model naked .
obj(painted, model)
acl(model, naked)

If the nominal head is missing, the secondary predicate must be attached as advcl of the verbal predicate, even though it is an adjective, not an adverb. There is a second predication and the adjective heads the predication (just like in She is sad) and in this case there are simply no other words expressing this second predication:

Vstoupila do místnosti smutná . \n She-entered to room sad .
advcl(Vstoupila, smutná)
advcl(She-entered, sad)

The remaining, most subtle case is optional resultatives. For these, we uniformly use xcomp:

He painted the house blue .
obj(painted, house)
xcomp(painted, blue)

Even though the resultative is optional here, one may argue that it is still a complement (an argument) of the higher verb (he is painting something blue), in a way that is not true of depictives. Such an analysis of optional resultatives as core arguments is adopted for English by Huddleston and Pullum (p. 262). In LFG terms, we would say that the verb has acquired a new subcategorization frame by application of a lexical rule, and that this frame includes an additional xcomp argument. Such an analysis is buttressed by the fact that normally intransitive verbs like to bark can also form similar resultatives by gaining a new subcategorization which adds both a dobj and an xcomp, as in the example below.

The dog barked the neighbors awake .
obj(barked, neighbors)
xcomp(barked, awake)