Some Results Regarding Tree Homomorphic Feature Structure Grammar and the Empty String
نویسنده
چکیده
In th is a rtic le we focus on som e restric tions we m ay im pose on Tree H om om orphic F ea tu re S tru c tu re G ram m ar (THFSG) regard ing th e em pty strin g . A fter defin ing the re s tric tio n s , we prove som e closure p ro p erties of th e two new classes of languages these re s tr ic tio n s give us. F u rtherm ore , we estab lish th a t th e m em bersh ip prob lem is PSPA C E com plete for THFSGs w ithou t em p ty p ro d u c tio n s in th e ph rase s tru c tu re ru les.
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