% "Learn Prolog Now!" Exercise 2.4

word(astante,a,s,t,a,n,t,e).
word(astoria,a,s,t,o,r,i,a).
word(baratto,b,a,r,a,t,t,o).
word(cobalto,c,o,b,a,l,t,o).
word(pistola,p,i,s,t,o,l,a).
word(statale,s,t,a,t,a,l,e). 

crossword(V1,V2,V3,H1,H2,H3) :-
	word(V1,_,H1V1,_,H2V1,_,H3V1,_),
	word(V2,_,H1V2,_,H2V2,_,H3V2,_),
	word(V3,_,H1V3,_,H2V3,_,H3V3,_),
	word(H1,_,H1V1,_,H1V2,_,H1V3,_),
	word(H2,_,H2V1,_,H2V2,_,H2V3,_),
	word(H3,_,H3V1,_,H3V2,_,H3V3,_), V1 \= H1.