Abstract. A formula ψ(Y ) is a selector for a formula ϕ(Y ) in a structure M if there exists a unique Y that satisfies ψ in M and this Y also satisfies ϕ. A formula ψ(X, Y )...
This tutorial will present an overview of the use of Monadic Second-Order Logic to describe sets of finite graphs and graph transformations, in relation with the notions of tree-w...