[eclipse-clp-users] Order of constraints

Dear Clp users,



  I am trying the following.



:- lib(ic).
solve(Nr, Hosts):-

Nr #> 6,
problem(Nr, Hosts),

writeln(end).

problem(Nr, Hosts):-

        findall(boat{nr:Nr,cap:Cap,crew:Crew,sorting:Space},
                (boat(Nr,Cap,Crew)),Hosts).

boat(1 , 6 , 2).
boat(2 , 8 , 2).
boat(3 , 12 , 2).
boat(4 , 12 , 2).
boat(5 , 12 , 4).
boat(6 , 12 , 4).
boat(7 , 12 , 4).
boat(8 , 10 , 1).
boat(9 , 10 , 2).



The output is following which is right:-

?- solve(Nr, Hosts).
Nr = Nr{7 .. 1.0Inf}
Hosts = [boat{nr : 7, cap : 12, crew : 4, sorting : _515}, boat{nr : 8, cap : 10, crew : 1, sorting : _540}, boat{nr : 9, cap : 10, crew : 2, sorting : _565}]
Yes (0.02s cpu)

------------------------------------------------------------------------------------------------------------

Now I change the script where I change the order of constraints in solve.

:- lib(ic).
solve(Nr, Hosts):-

problem(Nr, Hosts),
Nr #> 6,

writeln(end).

problem(Nr, Hosts):-

        findall(boat{nr:Nr,cap:Cap,crew:Crew,sorting:Space},
                (boat(Nr,Cap,Crew)),Hosts).

boat(1 , 6 , 2).
boat(2 , 8 , 2).
boat(3 , 12 , 2).
boat(4 , 12 , 2).
boat(5 , 12 , 4).
boat(6 , 12 , 4).
boat(7 , 12 , 4).
boat(8 , 10 , 1).
boat(9 , 10 , 2).



Now the output is the following:-

?- solve(Nr, Hosts).
Nr = Nr{7 .. 1.0Inf}
Hosts = [boat{nr : 1, cap : 6, crew : 2, sorting : _478}, boat{nr : 2, cap : 8, crew : 2, sorting : _503}, boat{nr : 3, cap : 12, crew : 2, sorting : _528}, boat{nr : 4, cap : 12, crew : 2, sorting : _553}, boat{nr : 5, cap : 12, crew : 4, sorting : _578}, boat{nr : 6, cap : 12, crew : 4, sorting : _603}, boat{nr : 7, cap : 12, crew : 4, sorting : _628}, boat{nr : 8, cap : 10, crew : 1, sorting : _653}, boat{nr : 9, cap : 10, crew : 2, sorting : _678}]
Yes (0.00s cpu)



My problem is I cannot control the sequence in which constrants appear in my script as it is autogenerated. Is there any other way to handle this.

One way is the following:-

:- lib(ic).
solve(Nr, Hosts):-

problem(Nr, Hosts),

writeln(end).

problem(Nr, Hosts):-

        findall(boat{nr:Nr,cap:Cap,crew:Crew,sorting:Space},
                (boat(Nr,Cap,Crew),Nr #> 6),Hosts).

boat(1 , 6 , 2).
boat(2 , 8 , 2).
boat(3 , 12 , 2).
boat(4 , 12 , 2).
boat(5 , 12 , 4).
boat(6 , 12 , 4).
boat(7 , 12 , 4).
boat(8 , 10 , 1).
boat(9 , 10 , 2).



But it wont work for me. I will the constraint Nr #> 6 only in solve. Please help.



Thanks and Regards,

Shrirang Edgaonkar

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