Impersonal diathesis #5
Description
In the impersonal diathesis, the subject of the sentence is an expletive. The relation between the main verb and the expletive subject is noted expl:subj in UD and subj:expl in SUD. Even if these relations are used in other cases, the conversion between them is not a problem.
The subject in the canonical diathesis becomes the direct object in the impersonal diathesis
Example:
Canonical diathesis: deux personnes arrivent (two people are coming)
Impersonal diathesis: il arrive deux personnes (there are two people coming)
In SUD, the relation between the verb and the object, which is the subject in the canonical diathesis, is noted comp:obj@agent.
In UD, it is noted csubj or nsubj as in the canonical diathesis, because the relation which is considered is deep subject.
When converting from UD to SUD, we must distinguish deep subjects in the impersonal diathesis from canonical subjects. In most cases, we can use the context to do this, but in some cases the expletive subject is far from the main verb, as in the following example.
Il peut être arrivé un malheur (Something bad may have happened)
The expletive subject "Il" is distant from the verb "arrivé".
To facilitate the conversion, I propose to add extension impers to nsubj or csubj for the deep subjects in the impersonal diathesis. In the previous example, this would give: arrivé -[nsubj:impers]-> malheur.
The impersonal diathesis may be combined with the passive diathesis, as in the following example.
Il peut être demandé beaucoup d'attention (It may require a lot of attention)
The object of "demandé" is "beaucoup". The relation is currently noted comp:obj@pass in SUD and nsubj:pass in UD. I propose to replace nsubj:pass (csubj:pass) by nsubj:impers (csubj:impers) to distinguish this function in the impersonal diathesis of the canonical passive subject and to facilitate the conversion from UD to SUD. The passive voice can be recovered with the passive auxiliary.