
<ConsistencyModule:> sum(+Collection,+Rel,?Sum)

   Constrains the sum of the elements of Collection to satisfy the relation sum(Collection) Rel Sum.

Arguments
   Collection          Collection of integers or domain variables.
   RelOp               One of the atom: #>, #>=, #<, #=<, #=, #\=
   Sum                 Variable or integer

Type
   library(gfd)

Description
          Constrains the sum of the elements in Collection to satisfy
          the relation sum(Collection) Rel Sum.
	  
          Rel can be one of #>, #>=, #<, #=<, #=, #\= (or equivalently,
          >, >=, <, =<, =, \=).
	  
	  Any input variables which are not already domain variable will be
          turn into domain variables with default bounds.
	  
          You may find it more convenient to embed sum(Collections,RelOp) 
          in a constraint expression.
	  
          ConsistencyModule is the optional module specification to give the 
          consistency level for the propagation for this constraint: 
          gfd_bc for bounds consistency, and 
          gfd_gac for domain (generalised arc) consistency.
          
          Domain consistency is different from bounds consistency only if
          Rel is #=.
          
          This constraint is known as sum_ctr in the global constraint 
          catalog, and is implemented using Gecode's linear() constraint.
          
    

See Also
   sum / 4
