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prologeclipse-clp

Constraint over the integer division

I have the following statement in prolog (Eclipse CLP):

?-X::1..100,  X/5 #= 2, X = 12.

The result is No.. I want to check that the integer division of X over 5 is equal to 2 or not. If I write the following statement:

?-X::1..100,  X//5 #= 2, X = 12.

I will get the following error:

instantiation fault in //(X{1 .. 100}, 5, _703)

So, the question is how can I check the integer division for the variable X?

Solution

  • I assume you are using library(ic), which currently does not directly support flooring or truncating divisions. You can reformulate your condition by introducing a "remainder" variable and using multiplication:

    ?- X::1..100, Rem::0..4, X #= 5*2 + Rem, X = 13.
X = 13
Rem = 3
Yes (0.00s cpu)