unix% xsb Start XSB, usually located in $XSB_DIR/bin
[xsb_configuration loaded]
[sysinitrc loaded]
[packaging loaded]
XSB Version 2.6 (Duff) of June 24, 2003
[i686-pc-linux-gnu; mode: optimal; engine: slg-wam; gc: indirection; scheduling: local]
| ?- [user]. Enter mode to type predicates & rules.
[Compiling user]
edge(1,2).
edge(2,3).
edge(2,4).
reachable(X,Y) :- edge(X,Y).
reachable(X,Y) :- edge(X,Z), reachable(Z, Y).
<Control-D> Done with terminal mode
[user compiled, cpu time used: 0.0500 seconds]
[user loaded]
yes
| ?- reachable(X,Y).
X = 1
Y = 2; Type a semi-colon repeatedly
X = 2
Y = 3;
X = 2
Y = 4;
X = 1
Y = 3;
X = 1
Y = 4;
no
| ?- halt. Command to Exit XSB
End XSB (cputime 0.15 secs, elapsetime 96.23 secs)
unix%
The above program describes a graph of edges, and a rule to determine which nodes are reachable from other nodes, as in this diagram:
You can also load a program in a file. Name the file with the .P extension. For example, if you have a file named sports.P, here's how to run it.
unix% cat sports.P Here's what the file looks like
:- auto_table.
likes(ellen,tennis).
likes(john,football).
likes(tom,baseball).
likes(eric,swimming).
likes(mark,tennis).
likes(bill, X) :- likes(tom,X).
unix% xsb
[xsb_configuration loaded]
[sysinitrc loaded]
[packaging loaded]
XSB Version 2.6 (Duff) of June 24, 2003
[i686-pc-linux-gnu; mode: optimal; engine: slg-wam; gc: indirection; scheduling: local]
| ?- [sports]. Load and run sports.P
[sports loaded]
yes
| ?- likes(bill, baseball).
yes
| ?- likes(bill, tennis).
no
| ?- halt.
End XSB (cputime 0.09 secs, elapsetime 132.97 secs)
unix%End XSB (cputime 0.09 secs, elapsetime 132.97 secs)
unix%