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Resumptive pronoun

SYNTAX: pronoun which appears in the position of the variable bound by a wh-phrase. EXAMPLE: in (i) him is a resumptive pronoun bound by who and interpreted as a bound variable.

(i) I wonder [whoi they think [that [if Mary marries himi ] then 
    everybody will be happy]]
The appearance of resumptive pronouns is marginal in standard English, but quite acceptable in French and colloquial English. Theoretically, the construction is exceptional as well. Since the if-clause creates an Adjunct Island, extraction of who out of the object position of marries is ungrammatical, as shown in (ii):
(ii) * I wonder [whoi they think [that [if Mary marries ei ] then 
       everybody will be happy]]
The resulting chain presumably violates subjacency. In (i), on the other hand, who has not been moved. But being an operator, it must bind a variable, in this case the resumptive pronoun him.
LIT. Chomsky, N. (1982)
Chomsky, N. (1981)
Zribi-Hertz, A. (1984)