clpfd: #==> / 2

/usr/lib/swipl/library/clp/clpfd.pl

library
- clp
  - clpfd.pl -- CLP(FD): Constraint Logic Programming over Finite Domains
    - in/2
    - ins/2
    - indomain/1
    - label/1
    - labeling/2
    - all_different/1
    - all_distinct/1
    - sum/3
    - scalar_product/4
    - #>=/2
    - #=</2
    - #=/2
    - #\=/2
    - #>/2
    - #</2
    - #\/1
    - #<==>/2
    - #==>/2
    - #<==/2
    - #/\/2
    - #\//2
    - #\/2
    - lex_chain/1
    - tuples_in/2
    - serialized/2
    - element/3
    - global_cardinality/2
    - global_cardinality/3
    - circuit/1
    - cumulative/1
    - cumulative/2
    - disjoint2/1
    - automaton/3
    - automaton/8
    - transpose/2
    - zcompare/3
    - chain/2
    - fd_var/1
    - fd_inf/2
    - fd_sup/2
    - fd_size/2
    - fd_dom/2
    - fd_degree/2
    - in_set/2
    - fd_set/2
    - is_fdset/1
    - empty_fdset/1
    - fdset_parts/4
    - empty_interval/2
    - fdset_interval/3
    - fdset_singleton/2
    - fdset_min/2
    - fdset_max/2
    - fdset_size/2
    - list_to_fdset/2
    - fdset_to_list/2
    - range_to_fdset/2
    - fdset_to_range/2
    - fdset_add_element/3
    - fdset_del_element/3
    - fdset_disjoint/2
    - fdset_intersect/2
    - fdset_intersection/3
    - fdset_member/2
    - fdset_eq/2
    - fdset_subset/2
    - fdset_subtract/3
    - fdset_union/3
    - fdset_union/2
    - fdset_complement/2
  - clpb.pl -- CLP(B): Constraint Logic Programming over Boolean Variables

#==>(?P, ?Q): P implies Q. See reification.