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alldifferent(+Vars)
All members of Vars are different
- Vars
- A collection (a la collection_to_list/2) of variables or integers
Description
Constrains all elements of a collection to be pairwise different (and
integral). This is an implementation with the same semantics as the
standard alldifferent/1 constraint, but with stronger propagation
behaviour. It checks for exhaustion of all sub-ranges of possible
values.
Any input variables which do not already have finite bounds will
be given default bounds of -10000000 to 10000000.
Examples
?- length(Xs,5), Xs::1..4, alldifferent(Xs).
no (more) solution.
?- [X1,X2]::1..2, [X3,X4,X5]::1..5, alldifferent([X1,X2,X3,X4,X5]).
X1 = X1{[1, 2]}
X2 = X2{[1, 2]}
X3 = X3{[3..5]}
X4 = X4{[3..5]}
X5 = X5{[3..5]}
Delayed goals:
alldifferent([X1{[1, 2]}, X2{[1, 2]}], 1)
alldifferent([X3{[3..5]}, X4{[3..5]}, X5{[3..5]}], 1)
See Also
ic_symbolic : alldifferent / 1, ic_global : alldifferent / 1, fd : alldifferent / 1, ic : alldifferent / 1, sd : alldifferent / 1, alldifferent / 2, lists : collection_to_list / 2