Backtrack

[Tiago Rodrigues Antao]

Hi!

I am new to Erlang. Being one of my working languages Prolog (used, believe it 
or not, in a production environment) I tried to do the typical 
parents/grandparents example of Prolog:

parent(jane, joe).
parent(joe, mark).

As far as I can see Erlang has no concept of parameters that are both 
input/output and of backtrack. Am I wrong?

I would like to do:
?- parent(X,Y).
X = jane
Y = joe
;
X = joe
Y = mark
;
no

Erlang has no provisions for this, at least that is my (very limited) 
understanding. Please correct me if I am wrong.

Thanks a lot,
Tiago