ABSTRACT
Forconvenienceofreference,hereagainarethefourphrasestructureruleswhich,accordingtothepreviouschapter,thebaseof thesyntaxmustcontain:
(i)S-+NP+PredP (ii)PredP-+Aux+{~p}
Adj NP
(iii)NP-+Det+N (iv)VP-+V+{NP}
Adj
Wenowturnourattentiontothesymbolswhicharemanipulated bytheserules.Thereareninesymbols:S,PredP,NP,VP,N,V,Adj, DetandAux.AllexceptSarenamesfortypesofconstituents,for constitqentpartsofhigher-levelunits.Siscalledtheinitialsymbol ofthegrammar-theforceoftheterm'initial'willbecomeobvious whenweconsiderderivationalprocessesinthelatterhalfofthis chapter:itisthesymbolwithwhicheveryderivationbegins.It standsfortheclassofobjects-underlyingP-markers-whichthe PSGdefines.NotethatSdoesnotstandfor'sentence':'sentence' isageneraltermforoneoftheclassofobjectswhichthegrammar asawhole,andnotjustthephrase-structuresection,defines.A sentencemayconsistofoneSorofmorethanone.
