🚀 go-pugleaf

In article <ARI.HUTTUNEN.91Jun23021130@wonderwoman.hut.fi>, Ari.Huttunen@hut.fi (Ari Juhani Huttunen) writes:
> I would like to know if this is a good way to represent graphs
> or an ugly hack.  The idea is to have fast access to the current
> location in the graph and its near neighbours.

> graph(X) :-
> 	X = vertice(x,[A,B,C]),
> 	A = vertice(a,[D,X]),
....
It's an ugly hack.  It is going to get you into big trouble is some
Prologs.  The file GRAPHS.PL in the DEC-10 Prolog library provides
several representations for graphs, including
	list of edges					-- sorted!
	list of node-(list of neighbours)		-- sorted!
These representations appear to be adequate for a great many tasks,
allowing the graph algorithms I was interested in to be coded in
Prolog with the same asymptotic cost as in Pascal or C (admittedly
with higher constant factors).  Another representation would be the
adjacency matrix, represented as a quad-tree, which works rather
nicely.  I would be interested to know which graph algorithms you
are implementing.

By the way, it's "vertEX", not "vertICE".
-- 
I agree with Jim Giles about many of the deficiencies of present UNIX.