Prolog-20 version 1.0 Copyright (C) 1981, 1983 by D. Warren, F. Pereira and L. Byrd | ?- [hier1]. hier1 consulted 506 words 0.18 sec. yes | ?- ap[fly,X]. ***syntax error*** ap ***here*** [fly,X]. | ap(fly,X)? | ap(fly,X). ***syntax error*** ap(fly,X) ***here*** ? ap(fly,X). | ap(fly,X). X = tweety yes | ?- ordinarily(adelie,X).