Fig. 6

Example of two solutions \(S_1\) (left, frozen) and \(S_2\) (right, extensible) in \(G^*(v)\). The cliques \(c_1\) and \(c_2\) are children of c(v). Each of \(S_1\) and \(S_2\) contains two alternating elements (solid black lines). The frozen solution is obtained with the juxtaposition of two frozen solutions in \(c_1\) and \(c_2\). The extensible solution is obtained with the juxtaposition of a frozen solution in \(c_1\) and with the merge between v and an extensible solution in \(c_2\)