I mean it resolves but... how do I know I followed the rules

startJug(0,0):-
	solveJug(0,0),!.
startJug(_,_):-
	write("Start with 0,0 ya dang goof."),fail,!.

solveJug(_,2):- !.
solveJug(Jug1Before,Jug2Before):-
	changeJug(Jug1Before,Jug2Before,Jug1After,Jug2After),
	 solveJug(Jug1After,Jug2After).

changeJug(Jug1Before,Jug2Before,3,Jug2After):- % Fill Jug1 with Jug2.
	Jug1Before \= 3,
	 Jug2After is Jug2Before - (3 - Jug1Before),
	 Jug2After >= 0.
changeJug(Jug1Before,Jug2Before,Jug1After,0):- % Empty Jug2 into Jug1.
	Jug2Before \= 0,
	 Jug1After is Jug1Before + Jug2Before,
	 Jug1After =< 3.
changeJug(Jug1Before,Jug2Before,0,Jug2Before):- Jug1Before = 3. % Empty full Jug1.
changeJug(Jug1Before,Jug2Before,Jug1Before,4):- Jug2Before < 4. % Fill Jug2.
changeJug(Jug1Before,Jug2Before,0,Jug2Before):- Jug1Before > 0. % Empty partial Jug1.