list of ordered pairs in prolog -

i trying implement prolog method take number , return list of possible ordered pairs both x , y less number given. example

genxy(2,r). 

should return

r=[0,0]; r=[0,1]; r=[1,0]; r=[1,1]. 

i having trouble understanding how implement this. have written code

genn(n,r) :-     n1 n-1,     between(0,n1,r). 

which give following output when executed

genn(3,r). r=0; r=1; r=2; 

and believe should use forall implement genxy don't understand how go doing

just use between/3 twice:

?- n = 2, r = x-y, succ(n0, n), between(0, n0, x), between(0, n0, y).  r = 0-0; r = 0-1; r = 1-0; r = 1-1;