- ?Vars &:: +Domain
- All elements of Vars have a value in the domain Domain
- ?X &< ?Y
- X is before Y in the domain order
- &<(?X, ?Y, ?Bool)
- Reified version of X &< Y
- ?X &= ?Y
- X is the same domain value as Y
- &=(?X, ?Y, ?Bool)
- Reified version of X &= Y
- ?X &=< ?Y
- X is before or equal to Y in the domain order
- &=<(?X, ?Y, ?Bool)
- Reified version of X &=< Y
- ?X &> ?Y
- X is after Y in the domain order
- &>(?X, ?Y, ?Bool)
- Reified version of X &> Y
- ?X &>= ?Y
- X is after or equal to Y in the domain order
- &>=(?X, ?Y, ?Bool)
- Reified version of X &>= Y
- ?X &\= ?Y
- X is different from Y in the domain
- &\=(?X, ?Y, ?Bool)
- Reified version of X &\= Y
- alldifferent(?List)
- All elements of List are different
- alldifferent(?List, ?Cap)
- No domain value occurs more than Cap times in List
- atmost(++N, +List, ++Value)
- Value occurs N times in List
- element(?Index, ++List, ?Value)
- Value is the Index'th element of List
- get_domain_as_list(?, ?)
- No description available
- indomain(?X)
- Nondeterministically instantiate to domain values
- is_exact_solver_var(?)
- No description available
- is_solver_var(?)
- No description available
- msg(?X, ?Y, -MSG)
- MSG is the most specific generalisation of X and Y representable with ic-symbolic domain variables
- occurrences(+Value, +List, ?N)
- Value occurs N times in List
- rotate(?X, ?C, ?Y)
- Y is C places after X in the (cyclic) domain order
- rotate(?X, ?C, ?Y, ?Bool)
- Reified version of rotate(X,C,Y)
- shift(?X, ?C, ?Y)
- Y is C places after X in the domain order
- shift(?X, ?C, ?Y, ?Bool)
- Reified version of shift(X,C,Y)
- symbol_domain_index(?X, -Domain, -Index)
- Map a symbolic domain variable/value to integer variable/value
- symbols_domain_indices(+Xs, ?Domain, -Is)
- Map symbolic domain variables/values to integer variables/values
- export op(700, xfx, &::)
- export op(700, xfx, &=)
- export op(700, xfx, &\=)
- export op(700, xfx, &<)
- export op(700, xfx, &=<)
- export op(700, xfx, &>)
- export op(700, xfx, &>=)
This library is an add-on to library(ic) and implements variables over ordered symbolic domains, and constraints over such variables. This is in contrast to the basic library(ic), which implements only variables over numeric domains.
?- local domain(weekday(mo,tu,we,th,fr,sa,su)).
declares a domain with name 'weekday' and values 'mo', 'tu' etc.
The domain values are implicitly ordered, with 'mo' corresponding to 1,
until 'su' corresponding to 7.
Domain values must be unique within one ECLiPSe module, i.e. a symbolic
value can belong to at most one domain.
?- X &:: weekday.
X = X{[mo, tu, we, th, fr, sa, su]}
Yes (0.00s cpu)
or multiple variables using &:: /2.
?- [X, Y] &:: weekday, X &< Y.
X = X{[mo, tu, we, th, fr, sa]}
Y = Y{[tu, we, th, fr, sa, su]}
Yes (0.00s cpu)
?- X &:: weekday, X &=< we.
X = X{[mo, tu, we]}
Yes (0.00s cpu)
Internally, symbolic domains are mapped to integer ranges from 1 up to the number of domain elements. The first value in the domain declaration corresponds to 1, the second to 2 and so on. Similarly, symbolic domain variables can be mapped to a corresponding IC integer variable. This mapping is accessible through the predicate symbol_domain_index/3:
?- symbol_domain_index(fr, D, I).
D = weekday
I = 5
Yes (0.00s cpu)
?- X &:: weekday, symbol_domain_index(X, D, I).
X = X{[mo, tu, we, th, fr, sa, su]}
D = weekday
I = I{1 .. 7}
Yes (0.00s cpu)
?- X &:: weekday, X &\= we, symbol_domain_index(X, D, I).
X = X{[mo, tu, th, fr, sa, su]}
D = weekday
I = I{[1, 2, 4 .. 7]}
Yes (0.00s cpu)
The integer variable I mirrors the domain of the symbolic variable
X and vice versa.
Because of the mapping of symbols to integers, new constraints over symbolic variables can be implemented simply by placing numeric (IC) constraints on the corresponding integer variables.
Similarly, the facilities of the ic_search library can be exploited when working with symbolic variables. Instead of labeling the symbolic variables, one can use the various facilities of ic_search to label the corresponding integer variables instead.
For efficiency reasons, the 'constrained' suspension list of the symbolic variable does not automatically get woken every time the domain changes (although it does get woken when the domain is initially attached, and when the variable gets instantiated). There are two solutions: (1) instead of suspending goals on the constrained-list of the symbolic variable, suspend them on the constrained-list of the corresponding integer variable. (2) Use a forwarding demon that suspends on the constrained-list of the integer variable and wakes the constrained-list of the symbolic variable:
symbol_domain_index(X, Domain, X_ic),
suspend(notify_constrained(X), 2, X_ic->constrained)