Enrico Oliosi wrote:
Ho fatto l'analisi del seguente programma BEGINPRG Read(i); j:=0; IF (i >= 0) THEN { j:= i+2; [p1]={j=0; i>=0; j-i=2} } ELSE { j:= i; [p2]={j=0; -i>0; j-i=0} } FI; [1=0] ENDPRG
e quando ho fatto la chiusura convessa utilizzando la chiamata
[p1].poly_hull_assign_and_minimize([p2]);
Il risultato e' stato: 1=0. Il poliedro vuoto.
Dear Enrico,
what you obtain is not surprising at all: since both p1 and p2 are empty polyhedra, their poly-hull is the empty polyhedron.
(se utilizzo la chiamata [p1].poly_hull_assign([p2]) la poly_hull torna [p2]);
This is still OK: the method poly_hull_assign() does not minimize the result and, since p1 is empty it simply gives you back p2.
I think that the problem is elsewhere: the constraint `j=0' should not, I believe, be in p1 nor in p2. Please do not hesitate to come back to us if I have not addressed your questions properly. Cheers,
Roberto