In Chomskyan syntax, PRO (also called big PRO, to distinguish it from pro in speech) is a null noun phrase that occurs in a position where it does not get case (or gets null case). PRO's meaning is determined by control.
PRO is posited in particular for the notional subject of infinitives:
- Masha asked Jaime [PRO to help her].
PRO was introduced by Chomsky 1981.
- Chomsky, Noam. 1981. Lectures in Government and Binding. Dordrecht: Foris.
- Vanden Wyngaerd, Guido. 1994. PRO-Legomena: Distribution and reference of infinitival subjects. Berlin: Mouton de Gruyter.
German PRO (de)