\input zb-basic \input zb-ioport \iteman{io-port 06033767} \itemau{Courcelle, Bruno} \itemti{On the model-checking of monadic second-order formulas with edge set quantifications.} \itemso{Discrete Appl. Math. 160, No. 6, 866-887 (2012).} \itemab Summary: We extend clique-width to graphs with multiple edges. We obtain fixed-parameter tractable model-checking algorithms for certain monadic second-order graph properties that depend on the multiplicities of edges, with respect to this ``new" clique-width. We define special tree-width, the variant of tree-width relative to tree-decompositions such that the boxes that contain a vertex are on a path originating from some fixed node. We study its main properties. This definition is motivated by the construction of finite automata associated with monadic second-order formulas using edge set quantifications. These automata yield fixed-parameter linear algorithms with respect to tree-width for the model-checking of these formulas. Their construction is much simpler for special tree-width than for tree-width, for reasons that we explain. \itemrv{~} \itemcc{} \itemut{tree-width; clique-width; monadic second-order logic; graph decomposition; model-checking} \itemli{doi:10.1016/j.dam.2010.12.017} \end