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# <ConsistencyModule:> circuit_offset(+Succ,+Offset,++CostMatrix,?Cost)

Constrains elements in Succ (offset by Offset) to form a Hamiltonian circuit with cost Cost.
*Succ*
- A collection of N different (domain) variables or integers
*Offset*
- Offset for Succ (An integer)
*CostMatrix*
- A NxN matrix collection of integers.
*Cost*
- A (domain) variable or integer (array notation accepted).

## Description

Succ is a collection of N elements presenting a digraph of N nodes, where
the value of the i'th element of Succ - Offset represents the successor to
node i. The constraint enforces Succ to form a Hamiltonian circuit,
a path through every node in the graph, visiting each node once and
forming a circuit. Additionally,CostMatrix specifies the cost for
traversing between each pair of nodes:
CostMatrix[i,j] represents the cost of travelling from node i to j, and
Cost is constrained to the total cost for the circuit.

Note that the Gecode implementation of this constraint has index (node id)
starting from 0, rather than 1. The value of Offset is incremented by 1
when the constraint is posted to Gecode. A version of this constraint with
native Gecode indexing, i.e. without adjusting Offset, is available
as circuit_offset_g/4.

This constraint can be embedded in a constraint expression in its
functional form (without the last argument).

ConsistencyModule is the optional module specification to give the
consistency level for the propagation for this constraint:
gfd_gac for generalised arc consistency (domain consistency),
and gfd_vc for value consistency.

This constraint is implemented by Gecode's circuit() constraint (variant with
cost), using an offset of Offset + 1.

## See Also

circuit_offset_g / 4, circuit_offset / 2, circuit_offset / 5, circuit / 3