Average concurrence and entanglement swapping

We study the role of average concurrence in entanglement swapping quantum networks. begin with qubit pure states, and there is a very simple rule governing propagation multiple swaps. find similarly for when creating Greenberger-Horne-Zeilinger state from three entangled pairs. look at examples mixed states that relation gives an upper bound on what possible states. then move to qudits, where we make use I-concurrence. Here situation not as qubits, but some cases relatively straightforward results can be obtained.