Error: Underscore in binary relation in file underscore.dl at line 8
F(x,y) :- F(x,y), x > _.
----------------------^--
Error: Argument in fact is not constant in file underscore.dl at line 10
F("string",_).
-----------^---
Error: Underscore in head of rule in file underscore.dl at line 10
F("string",_).
-----------^---
Error: Underscore in head of rule in file underscore.dl at line 12
F(_,y) :- F(_,y).
--^---------------
4 errors generated, evaluation aborted
