Following is a demo of the her3.pl program.
phurd@phurd-X510UAR:~/Desktop/COG366WorkSite/prolog$ swipl
Welcome to SWI-Prolog (threaded, 64 bits, version 8.4.0)
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).
?- [her3].
true.
?- solve(X).
X = [[2, 1], [2, 2], [3, 2], [3, 3], [3, 4], [3, 5], [2, 5], [2|...]] [write]
X = [[2, 1], [2, 2], [3, 2], [3, 3], [3, 4], [3, 5], [2, 5], [2, 6]]
Action (h for help) ?