“…Our proofs are based on a classic result known as the complement spanning-tree matrix theorem [19], which expresses the number of spanning trees of a graph G as a function of the determinant of a matrix that can be easily constructed from the adjacency relation (adjacency matrix, adjacency lists, etc.) of the graph G. Calculating the determinant of the complement spanning-tree matrix seems to be a promising approach for computing the number of spanning trees of families of graphs of the form K n − H, where H posses an inherent symmetry (see [1,3,5,16,22,23]). In our cases, since neither trees nor quasi-threshold graphs possess any symmetry, we focus on their structural and algorithmic properties.…”