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From: Ari.Huttunen@hut.fi (Ari Juhani Huttunen)
Newsgroups: comp.lang.prolog
Subject: Representing graphs?
Message-ID: <ARI.HUTTUNEN.91Jun23021130@wonderwoman.hut.fi>
Date: 23 Jun 91 00:11:30 GMT
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Distribution: comp
Organization: Helsinki University of Technology, Finland
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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
it's near neighbours. And since SB-prolog doesn't encourage asserting and
the graph has to be created while running...

graph(X) :-
	X = vertice(x,[A,B,C]),
	A = vertice(a,[D,X]),
	D = vertice(d,[A]),
	B = vertice(b,[X,G]),
	C = vertice(c,[X,E]),
	E = vertice(e,[C,F]),
	G = vertice(g,[F,B]),
	F = vertice(f,[E,G]).

test :-
	graph(X),
	writevertice(X),
	move(X,Y),
	writevertice(Y),
	move(Y,Z),
	writevertice(Z).

move(vertice(_,[Y|Ys]),Y).	

writevertice(vertice(Name,ConnectedTo)) :-
	names(ConnectedTo,Names),
	write(Name),
	write('-->'),
	writelist(Names),
	nl.

names([vertice(Name,_)|Vertices],[Name|Names]) :-
	names(Vertices,Names).
names([],[]).

writelist([X|Xs]) :-
	write(X),
	writelist(Xs).
writelist([]).
--
Ari Huttunen		  
puhelin: 90-7285944		T{m{ tila vuokrattavana.