[ library(eplex) | The ECLiPSe Libraries | Reference Manual | Alphabetic Index ]

# lp_add_constraints(+Handle, +Constraints, ++Integers, -Indices)

Add new expandable constraints to the demon solver Handle.

Handle
  Handle to a solver state
Constraints
  A (possibly empty) list of expandable equality or inequality constraints
Integers
  A (possibly empty) list of problem variables to be considered as integers
Indices
  Indices for the constraints in Constraints

## Description

Add new expandable constraints (with possibly new variables) to a solver. An expandable constraint can be expanded when new variables are added to the problem. These constraints are in the form of having a constant on the right-hand side, and coefficients for the problem variables on the left. When new variables are added (via lp_add_columns/2), the coefficients for these variables can be given for the expandable constraints. Note that the constraints can only be expanded if there are no trigger conditions (i.e. the problem must be solved explicitly), or if the problem is not associated with an eplex instance. Otherwise, the added constraints are treated as normal (non-expandable) constraints.

Constraints is a list of expandable constraints. NewIntegers is a list of variables that the external solver should consider as integers, Indices is a list of the indices for the added constraints. It is returned by the predicate, and has the same length as Constraints. Each element in Indices is the index for the constraint in Constraints at the same position in the list. This index is used to refer to the constraint in lp_add_columns/2.

Operationally lp_add_constraints/4 behaves like lp_add_constraints/3, except that it never trigger the solver as a demon: The new constraints will be taken into account the next time the solver is run, and removed on backtracking. The constraints are normalised before being passed to the external solver. Unlike lp_add_constraints/3, they are not simplified, and no consistency checks are performed. If any of the constraints are ground, a type error is raised.

Note that variables in NewIntegers can be any problem variables.

### Resatisfiable

no

### Exceptions

(4) instantiation fault
  Handle, Constraints or Integers uninstantiated.
(5) type error
  Some constraint in Constraints is ground.
(5) type error
  Some constraint in Constraints is non-linear.
(40) stale object handle
  Handle not valid: solver state had been destroyed by cleanup

## See Also

lp_add_constraints / 3, lp_demon_setup / 5, lp_add / 3, lp_add_columns / 2, $= / 2, $=< / 2, $>= / 2, =:= / 2, =< / 2, >= / 2