How do we parse impersonal passive?

[Vsevolod]

Good morning everyone.
I was performing a syntactic analysis of the following sentence:

They say that he cheats

That is what I've got: [they] - subject; [say] - predicate; [that he cheats] - direct object (content clause)
BUT! When I transform it into a passive, its syntactic structure changes beyond recognition:

He is said to cheat

[He] - subject; [is said] must be the predicate; [to cheat] appears to be something repesented by the infinitive.

Could you, please, explain what this infintive might be and why?

Thank you in advance!


Seva

 

[PaulMatthews]

He is said [to cheat].

The bracketed infinitival clause is complement of the matrix verb "said". Such complements are sometimes called "catenative complements": "catenative" being derived from the Latin word for chain; in grammar, a chain of verbs.

In your example, the catenative complement is obligatory since it is required to complete the verb phrase.

 

[Vsevolod]

Thank you so very much, PaulMatthews; you have been of great help!:up::up::up:
The only thing that is left to understand is why such infinitive-clauses are referred to as "clauses". I thought that for a clause to be a clause it must comprise both the subject and the predicate. Could you, please, explain where I am wrong?

Thank you again.

Seva

 

[PaulMatthews]

Most non-finite clauses have no overt subject, but in a sense we understand them as having subjects. In you example, the subject is retrievable from the matrix clause and can only be "he": we understand that 'he cheats'. But "he" is not actually present in the subordinate clause, so we refer to it as the "understood subject".