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Welcome to SWI-Prolog (Multi-threaded, Version 5.6.24)
Copyright (c) 1990-2006 University of Amsterdam.
SWI-Prolog comes with ABSOLUTELY NO WARRANTY. This is free software,
and you are welcome to redistribute it under certain conditions.
Please visit http://www.swi-prolog.org for details.

For help, use ?- help(Topic). or ?- apropos(Word).

?- ['combosets.pro'].
% combosets.pro compiled 0.00 sec, 7,312 bytes

Yes
?- combo(set(a,b,c),C,X).
Correct to: combos(set(a, b, c), C, X)? 

C = combo(a, b)
X = extra(c) 

Yes
?- combo(set(1,2,3,7),C,X).
Correct to: combos(set(1, 2, 3, 7), C, X)? 

C = combo(1, 2)
X = extras(3, 7) ;

C = combo(1, 3)
X = extras(2, 7) ;

C = combo(1, 7)
X = extras(2, 3) ;

C = combo(2, 3)
X = extras(1, 7) ;

C = combo(2, 7)
X = extras(1, 3) ;

C = combo(3, 7)
X = extras(1, 2) ;

No
?- halt.
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