On Cayley's formula for counting trees in nested interval graphs.
On general dissections of a polygon.
On general dissections of a polygon. (Short Communication).
On growth rates of permutations, set partitions, ordered graphs and other objects.
On Hamiltonian cycles of complete -partite graphs
On number of covering arcs in orderings
On the asymptotic number of plane curves and alternating knots.
On the energy and spectral properties of the he matrix of hexagonal systems
The He matrix, put forward by He and He in 1989, is designed as a means for uniquely representing the structure of a hexagonal system (= benzenoid graph). Observing that the He matrix is just the adjacency matrix of a pertinently weighted inner dual of the respective hexagonal system, we establish a number of its spectral properties. Afterwards, we discuss the number of eigenvalues equal to zero of the He matrix of a hexagonal system. Moreover, we obtain a relation between the number of triangles...
On the enumeration of a class of plane multigraphs.
On the genus distribution of -dipoles.
On the k-gamma q-distribution
We provide combinatorial as well as probabilistic interpretations for the q-analogue of the Pochhammer k-symbol introduced by Díaz and Teruel. We introduce q-analogues of the Mellin transform in order to study the q-analogue of the k-gamma distribution.
On the monotone upper bound problem.
On the number of cut-vertices in a graph.
On the number of cycles in a graph
On the number of cycles in -connected graphs.
On the number of forests
On the number of genus one labeled circle trees.
On the number of labeled -arch graphs.
On the Number of Minimal 1-Steiner Trees.
On the number of planar orientations with prescribed degrees.