Hannes wrote:

	Yes, why not just use a standard Dictionary?
	
	If I have 
	
	Element A is related to B (both directions)
	
	I would just do
	
	d _ Dictionary new.
	d at: #A put: #B.
	d at: #B put: #A.
	
	Am I missing something?
	
Well, yes.  Practically everything, actually.
The point about a Dictionary is that it is a PARTIAL FUNCTION.
For any key, there is AT MOST ONE related value.

The point about a BinaryRelation is that it is a RELATION.
For any "key", there could be any number of related values.

So, supposing you have
    {(A,B),(A,C),(A,X),(B,C),(B,M),(C,A),(C,M),(M,X)}
just how do you do that using one standard Dictionary?
    d at: #A put: #B.	"so far so good"
    d at: #A put: #C.	"oops! just lost B!"

Also, you can only handle the case you did handle by falsifying
the semantics.  Given the relation {(A,B)},
    A snarklefests B
is TRUE, but
    B snarklefests A
is FALSE, so if
    d at: #A put: #B
is an appropriate way of saying that A snarklefests B,
then
    d at: #B put: #A
must say that B snarklefests A, which it doesn't.

Being NAVIGABLE in both directions is very very different from
being symmetric.  If A snarklefests B, I want to be able to find
A given B, _even_though_B_does_not_snarklefest_A_.