1		:- use_module(library(between)).
2
3		start(0).
4
5		trans(a, N, N1) :- N1 is N+1.
6		trans(a, N, N1) :- N1 is N+2.
7		trans(a, N, N1) :- N1 is N+3.
8	?	trans(a(D), N, N1) :- between(1, 3, D), N1 is N+D.
9	?	trans(a(A), N, N1) :- between(1, 3, D), number_codes(D, Codes), atom_codes(A, Codes), N1 is N+D.
10
11		prop(S, S).