A position is an edge either it's file or rank is an edge. Basics of prolog

Question

I've been trying out prolog since yesterday, and trying to define chess rules. In particular, I want to define either a square is an edge or not.

Here are the rules I thought of:

 A file is a thru h. 
 A rank is 1 thru 8. 
 A pos is a file and a rank. 
 h is an edge. 
 8 is an edge. 
 A position is an edge either it's file or rank is an edge.

I played around, but for example this goes stack overflow. how do I model this?

% Prolog %

file(b).
file(a).
file(h).
rank(8).
rank(4).
rank(5).

pos(F, R) :- file(F), rank(R).

edge(h).
edge(8).
edge(X) :- pos(X, Y),!,edge(X),edge(Y).
% I also tried this, but this bloats the space.
% edge(pos(F, R)) :- edge(F),edge(R).

corner(pos(edge, edge)).

%  edge(h). % true
%  edge(8). % true
%  edge(4). % false
%  edge(pos(h, 4)). % true
%  edge(pos(b, 5)). % false
%  edge(pos(b, 8)). % true
%

Answer 1

basic version:

file(a).
file(b).
file(c).
file(d).
file(e).
file(f).
file(g).
file(h).

rank(1).
rank(2).
rank(3).
rank(4).
rank(5).
rank(6).
rank(7).
rank(8).

position(F-R) :-
    file(F),
    rank(R).

edge(a-_).
edge(h-_).
edge(_-1).
edge(_-8).

corner(a-1).
corner(a-8).
corner(h-1).
corner(h-8).

then

?- corner(C).
C = a-1 ;
C = a-8 ;
C = h-1 ;
C = h-8

or positions which have rank > 3 and are edges and are not corners:

?- position(X), X=F-R, R > 3, edge(F-R), \+ corner(F-R).  
X = a-4 ;
X = a-5 ;
X = a-6 ;
X = a-7 ;
X = b-8

and you can collapse down file() and rank() rules using member/2 and between/2 if desired.