Логическая задача про студентов на велосипедах

DOMAINS
  name=symbol
PREDICATES
  student(name) 
  gorod(name)
  velo(name,name)
  fact(name,name)
  fact1(name,name) 
  rodom(name,name) 
  rodom_penza(name)
 
CLAUSES
  student(Person) if Person=sergey; Person=boris; 
    Person=leonid; Person=grigoriy; Person=viktor.
    
  gorod(City) if City=penza; City=lvov; 
    City=moscow; City=harkov; City=riga.
      fact(boris,penza).
  fact(viktor,moscow).
  fact(grigoriy,harkov).
  fact(sergey,riga).
    velo(Person,City) if student(Person), gorod(City),
   fact(Person,City),!; 
   student(Person),gorod(City), not(fact(Person,_)),
   not(fact(_,City)).
  
  fact1(boris,riga).
  fact1(viktor,lvov).
    rodom_penza(Person) if student(Person), X=penza,
   not(fact1(Person,_)), gorod(Unknown),
   not(Unknown=X),velo(Person,Unknown),
   rodom(viktor,Unknown).
     rodom(Person,X) if student(Person), gorod(X),
    fact1(Person,X),!;
    student(Person),not(Person=viktor),X=penza,
    rodom_penza(Person),!;
    student(Person),gorod(X),not(fact1(_,X)), 
    Person=viktor, not(X=penza), student(Person),
    not(fact1(Person,_)),velo(Person,X);
    student(Person),not(Person=viktor),gorod(X),
    not(X=penza),not(fact1(_,X)),
    not(fact1(Person,_)),gorod(City),not(City=X),
    velo(Person,City),
    not(rodom(viktor,X)),not(rodom(viktor,city)).
    goal
    rodom(Person,moscow).