[ library(fd) | Reference Manual | Alphabetic Index ]
deleteff(?Var, +List, -Rest)
Select from List the variable Var which has the smallest domain and return
the rest of the list.
- -Var
- A variable.
- -Rest
- A term unifying with a list of domain variables or integers.
- +List
- A list of domain variables or integers.
Description
This predicate is used in the labeling procedures. When we look for the
instantiation of a list of domain variables which is consistent with a
set of constraints, it is better to start with instantiations which are
most likely to fail, because this will cut down the size of the search
space considerably.
The predicate deleteff/3 selects the variable with the smallest
domain. If there are several variables with the same domain size,
the leftmost one in the list is taken. Constants are treated like
variables of domain size one. The list Rest is the same as List
except that the selected element is missing. In particular, any
existing list order is preserved.
Fail Conditions
Fails if List is nil.
Resatisfiable
No.
See Also
deleteffc / 3, indomain / 1, fd_search : search / 6