poole@CPSC-M-POOLE01 prolog % swipl
Welcome to SWI-Prolog (threaded, 64 bits, version 9.0.4)
SWI-Prolog comes with ABSOLUTELY NO WARRANTY. This is free software.
Please run ?- license. for legal details.

For online help and background, visit https://www.swi-prolog.org
For built-in help, use ?- help(Topic). or ?- apropos(Word).

?- use_module(library(clpfd)).
true.

?- X #< Y, Y #< Z, Z #< X.
Z#=<X+ -1,
X#=<Y+ -1,
Y#=<Z+ -1.

?- X #< Y, Y #< Z, Z #< X, X=17.
false.

?- ^D
% halt
poole@CPSC-M-POOLE01 prolog % swipl
Welcome to SWI-Prolog (threaded, 64 bits, version 9.0.4)
SWI-Prolog comes with ABSOLUTELY NO WARRANTY. This is free software.
Please run ?- license. for legal details.

For online help and background, visit https://www.swi-prolog.org
For built-in help, use ?- help(Topic). or ?- apropos(Word).

?- [funlog].
true.

?- ff(a,b) =.. X.
X = [ff, a, b].

?- ff(X,Y) =.. T, X=3, Y=7, E =..T.
X = 3,
Y = 7,
T = [ff, 3, 7],
E = ff(3, 7).

?- eval(7*fac(4),[],V).
V = 168 .

?- ^D
% halt
poole@CPSC-M-POOLE01 prolog % swipl
Welcome to SWI-Prolog (threaded, 64 bits, version 9.0.4)
SWI-Prolog comes with ABSOLUTELY NO WARRANTY. This is free software.
Please run ?- license. for legal details.

For online help and background, visit https://www.swi-prolog.org
For built-in help, use ?- help(Topic). or ?- apropos(Word).

?- [meta].
true.

?- prove(append(X,[B,a|Y],[a,b,c,a,d,a,g])).
X = [a, b],
B = c,
Y = [d, a, g] ;
X = [a, b, c, a],
B = d,
Y = [g] ;
false.

?- ^D
% halt
poole@CPSC-M-POOLE01 prolog % swipl
Welcome to SWI-Prolog (threaded, 64 bits, version 9.0.4)
SWI-Prolog comes with ABSOLUTELY NO WARRANTY. This is free software.
Please run ?- license. for legal details.

For online help and background, visit https://www.swi-prolog.org
For built-in help, use ?- help(Topic). or ?- apropos(Word).

?- [dprove].
true.

?- [elect_a].
true.

?- dprove(lit(L),[],A).
L = l1,
A = [up(s1), up(s2)] ;
L = l1,
A = [down(s1), down(s2)] ;
L = l2,
A = [up(s3)] .

?- ^D
% halt
poole@CPSC-M-POOLE01 prolog % swipl
Welcome to SWI-Prolog (threaded, 64 bits, version 9.0.4)
SWI-Prolog comes with ABSOLUTELY NO WARRANTY. This is free software.
Please run ?- license. for legal details.

For online help and background, visit https://www.swi-prolog.org
For built-in help, use ?- help(Topic). or ?- apropos(Word).

?- [trace2].
true.

?- [elect_b].
true.

?- solve(lit(l1),T).
T = if(lit(l1), if(light(l1), true)&if(ok(l1), true)&if(live(l1), if(connectedto(l1, w0), true)&if(live(w0), if(connectedto(w0, w1), if(up(...), true))&if(live(w1), if(..., ...)&if(..., ...))))) .

?- show(lit(l1)).
lit(l1) :-
   1: light(l1)
   2: ok(l1)
   3: live(l1)
|: 3.
live(l1) :-
   1: connectedto(l1,w0)
   2: live(w0)
|: 2.
live(w0) :-
   1: connectedto(w0,w1)
   2: live(w1)
|: 2.
live(w1) :-
   1: connectedto(w1,w3)
   2: live(w3)
|: 1.
connectedto(w1,w3) :-
   1: up(s3)
|: